diff --git a/include/grpc++/impl/call.h b/include/grpc++/impl/call.h
index 1fa44907797..d49102fa3e7 100644
--- a/include/grpc++/impl/call.h
+++ b/include/grpc++/impl/call.h
@@ -173,6 +173,7 @@ class CallOpSendInitialMetadata {
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_SEND_INITIAL_METADATA;
     op->flags = 0;
+    op->reserved = NULL;
     op->data.send_initial_metadata.count = initial_metadata_count_;
     op->data.send_initial_metadata.metadata = initial_metadata_;
   }
@@ -206,6 +207,7 @@ class CallOpSendMessage {
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_SEND_MESSAGE;
     op->flags = write_options_.flags();
+    op->reserved = NULL;
     op->data.send_message = send_buf_;
     // Flags are per-message: clear them after use.
     write_options_.Clear();
@@ -248,6 +250,7 @@ class CallOpRecvMessage {
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_RECV_MESSAGE;
     op->flags = 0;
+    op->reserved = NULL;
     op->data.recv_message = &recv_buf_;
   }
 
@@ -313,6 +316,7 @@ class CallOpGenericRecvMessage {
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_RECV_MESSAGE;
     op->flags = 0;
+    op->reserved = NULL;
     op->data.recv_message = &recv_buf_;
   }
 
@@ -350,6 +354,7 @@ class CallOpClientSendClose {
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
     op->flags = 0;
+    op->reserved = NULL;
   }
   void FinishOp(bool* status, int max_message_size) { send_ = false; }
 
@@ -383,6 +388,7 @@ class CallOpServerSendStatus {
     op->data.send_status_from_server.status_details =
         send_status_details_.empty() ? nullptr : send_status_details_.c_str();
     op->flags = 0;
+    op->reserved = NULL;
   }
 
   void FinishOp(bool* status, int max_message_size) {
@@ -416,6 +422,7 @@ class CallOpRecvInitialMetadata {
     op->op = GRPC_OP_RECV_INITIAL_METADATA;
     op->data.recv_initial_metadata = &recv_initial_metadata_arr_;
     op->flags = 0;
+    op->reserved = NULL;
   }
   void FinishOp(bool* status, int max_message_size) {
     if (recv_initial_metadata_ == nullptr) return;
@@ -453,6 +460,7 @@ class CallOpClientRecvStatus {
     op->data.recv_status_on_client.status_details_capacity =
         &status_details_capacity_;
     op->flags = 0;
+    op->reserved = NULL;
   }
 
   void FinishOp(bool* status, int max_message_size) {
diff --git a/include/grpc/byte_buffer.h b/include/grpc/byte_buffer.h
index 913e2a7697f..1433ffdf7e3 100644
--- a/include/grpc/byte_buffer.h
+++ b/include/grpc/byte_buffer.h
@@ -47,8 +47,12 @@ typedef enum {
 } grpc_byte_buffer_type;
 
 struct grpc_byte_buffer {
+  void *reserved;
   grpc_byte_buffer_type type;
   union {
+    struct {
+      void *reserved[8];
+    } reserved;
     struct {
       grpc_compression_algorithm compression;
       gpr_slice_buffer slice_buffer;
diff --git a/include/grpc/grpc.h b/include/grpc/grpc.h
index 5915dda2bae..f1046480110 100644
--- a/include/grpc/grpc.h
+++ b/include/grpc/grpc.h
@@ -202,13 +202,14 @@ typedef struct grpc_metadata {
   const char *key;
   const char *value;
   size_t value_length;
+  gpr_uint32 flags;
 
   /** The following fields are reserved for grpc internal use.
       There is no need to initialize them, and they will be set to garbage
      during
       calls to grpc. */
   struct {
-    void *obfuscated[3];
+    void *obfuscated[4];
   } internal_data;
 } grpc_metadata;
 
@@ -251,6 +252,7 @@ typedef struct {
   char *host;
   size_t host_capacity;
   gpr_timespec deadline;
+  void *reserved;
 } grpc_call_details;
 
 void grpc_call_details_init(grpc_call_details *details);
@@ -306,7 +308,13 @@ typedef struct grpc_op {
   grpc_op_type op;
   /** Write flags bitset for grpc_begin_messages */
   gpr_uint32 flags;
+  /** Reserved for future usage */
+  void *reserved;
   union {
+    /** Reserved for future usage */
+    struct {
+      void *reserved[8];
+    } reserved;
     struct {
       size_t count;
       grpc_metadata *metadata;
@@ -408,7 +416,7 @@ void grpc_shutdown(void);
 const char *grpc_version_string(void);
 
 /** Create a completion queue */
-grpc_completion_queue *grpc_completion_queue_create(void);
+grpc_completion_queue *grpc_completion_queue_create(void *reserved);
 
 /** Blocks until an event is available, the completion queue is being shut down,
     or deadline is reached.
@@ -419,7 +427,7 @@ grpc_completion_queue *grpc_completion_queue_create(void);
     Callers must not call grpc_completion_queue_next and
     grpc_completion_queue_pluck simultaneously on the same completion queue. */
 grpc_event grpc_completion_queue_next(grpc_completion_queue *cq,
-                                      gpr_timespec deadline);
+                                      gpr_timespec deadline, void *reserved);
 
 /** Blocks until an event with tag 'tag' is available, the completion queue is
     being shutdown or deadline is reached.
@@ -433,7 +441,7 @@ grpc_event grpc_completion_queue_next(grpc_completion_queue *cq,
     Completion queues support a maximum of GRPC_MAX_COMPLETION_QUEUE_PLUCKERS
     concurrently executing plucks at any time. */
 grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cq, void *tag,
-                                       gpr_timespec deadline);
+                                       gpr_timespec deadline, void *reserved);
 
 /** Maximum number of outstanding grpc_completion_queue_pluck executions per
     completion queue */
@@ -476,17 +484,17 @@ grpc_call *grpc_channel_create_call(grpc_channel *channel,
                                     gpr_uint32 propagation_mask,
                                     grpc_completion_queue *completion_queue,
                                     const char *method, const char *host,
-                                    gpr_timespec deadline);
+                                    gpr_timespec deadline, void *reserved);
 
 /** Pre-register a method/host pair on a channel. */
 void *grpc_channel_register_call(grpc_channel *channel, const char *method,
-                                 const char *host);
+                                 const char *host, void *reserved);
 
 /** Create a call given a handle returned from grpc_channel_register_call */
 grpc_call *grpc_channel_create_registered_call(
     grpc_channel *channel, grpc_call *parent_call, gpr_uint32 propagation_mask,
     grpc_completion_queue *completion_queue, void *registered_call_handle,
-    gpr_timespec deadline);
+    gpr_timespec deadline, void *reserved);
 
 /** Start a batch of operations defined in the array ops; when complete, post a
     completion of type 'tag' to the completion queue bound to the call.
@@ -500,7 +508,7 @@ grpc_call *grpc_channel_create_registered_call(
     containing just send operations independently from batches containing just
     receive operations. */
 grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
-                                      size_t nops, void *tag);
+                                      size_t nops, void *tag, void *reserved);
 
 /** Returns a newly allocated string representing the endpoint to which this
     call is communicating with. The string is in the uri format accepted by
@@ -532,7 +540,8 @@ char *grpc_channel_get_target(grpc_channel *channel);
     more on this. The data in 'args' need only live through the invocation of
     this function. */
 grpc_channel *grpc_insecure_channel_create(const char *target,
-                                           const grpc_channel_args *args);
+                                           const grpc_channel_args *args,
+                                           void *reserved);
 
 /** Create a lame client: this client fails every operation attempted on it. */
 grpc_channel *grpc_lame_client_channel_create(const char *target);
@@ -551,7 +560,7 @@ void grpc_channel_destroy(grpc_channel *channel);
     THREAD-SAFETY grpc_call_cancel and grpc_call_cancel_with_status
     are thread-safe, and can be called at any point before grpc_call_destroy
     is called.*/
-grpc_call_error grpc_call_cancel(grpc_call *call);
+grpc_call_error grpc_call_cancel(grpc_call *call, void *reserved);
 
 /** Called by clients to cancel an RPC on the server.
     Can be called multiple times, from any thread.
@@ -561,7 +570,8 @@ grpc_call_error grpc_call_cancel(grpc_call *call);
     remote endpoint. */
 grpc_call_error grpc_call_cancel_with_status(grpc_call *call,
                                              grpc_status_code status,
-                                             const char *description);
+                                             const char *description,
+                                             void *reserved);
 
 /** Destroy a call.
     THREAD SAFETY: grpc_call_destroy is thread-compatible */
@@ -600,14 +610,16 @@ grpc_call_error grpc_server_request_registered_call(
     be specified with args. If no additional configuration is needed, args can
     be NULL. See grpc_channel_args for more. The data in 'args' need only live
     through the invocation of this function. */
-grpc_server *grpc_server_create(const grpc_channel_args *args);
+grpc_server *grpc_server_create(const grpc_channel_args *args,
+                                void *reserved);
 
 /** Register a completion queue with the server. Must be done for any
     notification completion queue that is passed to grpc_server_request_*_call
     and to grpc_server_shutdown_and_notify. Must be performed prior to
     grpc_server_start. */
 void grpc_server_register_completion_queue(grpc_server *server,
-                                           grpc_completion_queue *cq);
+                                           grpc_completion_queue *cq,
+                                           void *reserved);
 
 /** Add a HTTP2 over plaintext over tcp listener.
     Returns bound port number on success, 0 on failure.
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index 5839d3ac2e4..6a1a6cbf305 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -964,7 +964,7 @@ static void call_on_done_recv(void *pc, int success) {
           next_child_call = child_call->sibling_next;
           if (child_call->cancellation_is_inherited) {
             GRPC_CALL_INTERNAL_REF(child_call, "propagate_cancel");
-            grpc_call_cancel(child_call);
+            grpc_call_cancel(child_call, NULL);
             GRPC_CALL_INTERNAL_UNREF(child_call, "propagate_cancel", 0);
           }
           child_call = next_child_call;
@@ -1265,18 +1265,22 @@ void grpc_call_destroy(grpc_call *c) {
   c->cancel_alarm |= c->have_alarm;
   cancel = c->read_state != READ_STATE_STREAM_CLOSED;
   unlock(c);
-  if (cancel) grpc_call_cancel(c);
+  if (cancel) grpc_call_cancel(c, NULL);
   GRPC_CALL_INTERNAL_UNREF(c, "destroy", 1);
 }
 
-grpc_call_error grpc_call_cancel(grpc_call *call) {
-  return grpc_call_cancel_with_status(call, GRPC_STATUS_CANCELLED, "Cancelled");
+grpc_call_error grpc_call_cancel(grpc_call *call, void *reserved) {
+  GPR_ASSERT(!reserved);
+  return grpc_call_cancel_with_status(call, GRPC_STATUS_CANCELLED, "Cancelled",
+                                      NULL);
 }
 
 grpc_call_error grpc_call_cancel_with_status(grpc_call *c,
                                              grpc_status_code status,
-                                             const char *description) {
+                                             const char *description,
+                                             void *reserved) {
   grpc_call_error r;
+  (void) reserved;
   lock(c);
   r = cancel_with_status(c, status, description);
   unlock(c);
@@ -1513,13 +1517,14 @@ static int are_write_flags_valid(gpr_uint32 flags) {
 }
 
 grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
-                                      size_t nops, void *tag) {
+                                      size_t nops, void *tag, void *reserved) {
   grpc_ioreq reqs[GRPC_IOREQ_OP_COUNT];
   size_t in;
   size_t out;
   const grpc_op *op;
   grpc_ioreq *req;
   void (*finish_func)(grpc_call *, int, void *) = finish_batch;
+  GPR_ASSERT(!reserved);
 
   GRPC_CALL_LOG_BATCH(GPR_INFO, call, ops, nops, tag);
 
diff --git a/src/core/surface/channel.c b/src/core/surface/channel.c
index 8692aa39030..308572c6342 100644
--- a/src/core/surface/channel.c
+++ b/src/core/surface/channel.c
@@ -168,7 +168,8 @@ grpc_call *grpc_channel_create_call(grpc_channel *channel,
                                     gpr_uint32 propagation_mask,
                                     grpc_completion_queue *cq,
                                     const char *method, const char *host,
-                                    gpr_timespec deadline) {
+                                    gpr_timespec deadline, void *reserved) {
+  GPR_ASSERT(!reserved);
   return grpc_channel_create_call_internal(
       channel, parent_call, propagation_mask, cq,
       grpc_mdelem_from_metadata_strings(
@@ -182,8 +183,9 @@ grpc_call *grpc_channel_create_call(grpc_channel *channel,
 }
 
 void *grpc_channel_register_call(grpc_channel *channel, const char *method,
-                                 const char *host) {
+                                 const char *host, void *reserved) {
   registered_call *rc = gpr_malloc(sizeof(registered_call));
+  GPR_ASSERT(!reserved);
   rc->path = grpc_mdelem_from_metadata_strings(
       channel->metadata_context, GRPC_MDSTR_REF(channel->path_string),
       grpc_mdstr_from_string(channel->metadata_context, method, 0));
@@ -200,8 +202,9 @@ void *grpc_channel_register_call(grpc_channel *channel, const char *method,
 grpc_call *grpc_channel_create_registered_call(
     grpc_channel *channel, grpc_call *parent_call, gpr_uint32 propagation_mask,
     grpc_completion_queue *completion_queue, void *registered_call_handle,
-    gpr_timespec deadline) {
+    gpr_timespec deadline, void *reserved) {
   registered_call *rc = registered_call_handle;
+  GPR_ASSERT(!reserved);
   return grpc_channel_create_call_internal(
       channel, parent_call, propagation_mask, completion_queue, 
       GRPC_MDELEM_REF(rc->path), 
diff --git a/src/core/surface/channel_create.c b/src/core/surface/channel_create.c
index 707d6156884..82ddfac757f 100644
--- a/src/core/surface/channel_create.c
+++ b/src/core/surface/channel_create.c
@@ -155,7 +155,8 @@ static const grpc_subchannel_factory_vtable subchannel_factory_vtable = {
                    - connect to it (trying alternatives as presented)
                    - perform handshakes */
 grpc_channel *grpc_insecure_channel_create(const char *target,
-                                           const grpc_channel_args *args) {
+                                           const grpc_channel_args *args,
+                                           void *reserved) {
   grpc_channel *channel = NULL;
 #define MAX_FILTERS 3
   const grpc_channel_filter *filters[MAX_FILTERS];
@@ -163,6 +164,7 @@ grpc_channel *grpc_insecure_channel_create(const char *target,
   subchannel_factory *f;
   grpc_mdctx *mdctx = grpc_mdctx_create();
   int n = 0;
+  GPR_ASSERT(!reserved);
   /* TODO(census)
   if (grpc_channel_args_is_census_enabled(args)) {
     filters[n++] = &grpc_client_census_filter;
diff --git a/src/core/surface/completion_queue.c b/src/core/surface/completion_queue.c
index 36d69cfe5fe..378b3f71a1c 100644
--- a/src/core/surface/completion_queue.c
+++ b/src/core/surface/completion_queue.c
@@ -69,8 +69,9 @@ struct grpc_completion_queue {
   plucker pluckers[GRPC_MAX_COMPLETION_QUEUE_PLUCKERS];
 };
 
-grpc_completion_queue *grpc_completion_queue_create(void) {
+grpc_completion_queue *grpc_completion_queue_create(void *reserved) {
   grpc_completion_queue *cc = gpr_malloc(sizeof(grpc_completion_queue));
+  GPR_ASSERT(!reserved);
   memset(cc, 0, sizeof(*cc));
   /* Initial ref is dropped by grpc_completion_queue_shutdown */
   gpr_ref_init(&cc->pending_events, 1);
@@ -166,9 +167,11 @@ void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, int success,
 }
 
 grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
-                                      gpr_timespec deadline) {
+                                      gpr_timespec deadline,
+                                      void *reserved) {
   grpc_event ret;
   grpc_pollset_worker worker;
+  GPR_ASSERT(!reserved);
 
   deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
 
@@ -232,11 +235,12 @@ static void del_plucker(grpc_completion_queue *cc, void *tag,
 }
 
 grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
-                                       gpr_timespec deadline) {
+                                       gpr_timespec deadline, void *reserved) {
   grpc_event ret;
   grpc_cq_completion *c;
   grpc_cq_completion *prev;
   grpc_pollset_worker worker;
+  GPR_ASSERT(!reserved);
 
   deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
 
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index cd1dc589e11..f8832759515 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -761,8 +761,10 @@ static const grpc_channel_filter server_surface_filter = {
 };
 
 void grpc_server_register_completion_queue(grpc_server *server,
-                                           grpc_completion_queue *cq) {
+                                           grpc_completion_queue *cq,
+                                           void *reserved) {
   size_t i, n;
+  GPR_ASSERT(!reserved);
   for (i = 0; i < server->cq_count; i++) {
     if (server->cqs[i] == cq) return;
   }
diff --git a/src/core/surface/server_create.c b/src/core/surface/server_create.c
index 1e26c67693d..9237eb5a904 100644
--- a/src/core/surface/server_create.c
+++ b/src/core/surface/server_create.c
@@ -36,8 +36,9 @@
 #include "src/core/surface/server.h"
 #include "src/core/channel/compress_filter.h"
 
-grpc_server *grpc_server_create(const grpc_channel_args *args) {
+grpc_server *grpc_server_create(const grpc_channel_args *args, void *reserved) {
   const grpc_channel_filter *filters[] = {&grpc_compress_filter};
+  (void) reserved;
   return grpc_server_create_from_filters(filters, GPR_ARRAY_SIZE(filters),
                                          args);
 }
diff --git a/src/core/transport/stream_op.c b/src/core/transport/stream_op.c
index a5dfec9d503..0a9669b0ab4 100644
--- a/src/core/transport/stream_op.c
+++ b/src/core/transport/stream_op.c
@@ -258,6 +258,7 @@ static void link_tail(grpc_mdelem_list *list, grpc_linked_mdelem *storage) {
   GPR_ASSERT(storage->md);
   storage->prev = list->tail;
   storage->next = NULL;
+  storage->reserved = NULL;
   if (list->tail != NULL) {
     list->tail->next = storage;
   } else {
diff --git a/src/core/transport/stream_op.h b/src/core/transport/stream_op.h
index 227320cf2a8..37f18b02d91 100644
--- a/src/core/transport/stream_op.h
+++ b/src/core/transport/stream_op.h
@@ -77,6 +77,7 @@ typedef struct grpc_linked_mdelem {
   grpc_mdelem *md;
   struct grpc_linked_mdelem *next;
   struct grpc_linked_mdelem *prev;
+  void *reserved;
 } grpc_linked_mdelem;
 
 typedef struct grpc_mdelem_list {
diff --git a/src/cpp/client/channel.cc b/src/cpp/client/channel.cc
index 1c2eecf7863..0582b59a6d5 100644
--- a/src/cpp/client/channel.cc
+++ b/src/cpp/client/channel.cc
@@ -67,7 +67,7 @@ Call Channel::CreateCall(const RpcMethod& method, ClientContext* context,
     c_call = grpc_channel_create_registered_call(
         c_channel_, context->propagate_from_call_,
         context->propagation_options_.c_bitmask(), cq->cq(),
-        method.channel_tag(), context->raw_deadline());
+        method.channel_tag(), context->raw_deadline(), nullptr);
   } else {
     const char* host_str = NULL;
     if (!context->authority().empty()) {
@@ -78,7 +78,7 @@ Call Channel::CreateCall(const RpcMethod& method, ClientContext* context,
     c_call = grpc_channel_create_call(c_channel_, context->propagate_from_call_,
                                       context->propagation_options_.c_bitmask(),
                                       cq->cq(), method.name(), host_str,
-                                      context->raw_deadline());
+                                      context->raw_deadline(), nullptr);
   }
   grpc_census_call_set_context(c_call, context->census_context());
   GRPC_TIMER_MARK(GRPC_PTAG_CPP_CALL_CREATED, c_call);
@@ -93,13 +93,14 @@ void Channel::PerformOpsOnCall(CallOpSetInterface* ops, Call* call) {
   GRPC_TIMER_BEGIN(GRPC_PTAG_CPP_PERFORM_OPS, call->call());
   ops->FillOps(cops, &nops);
   GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call->call(), cops, nops, ops));
+             grpc_call_start_batch(call->call(), cops, nops, ops, nullptr));
   GRPC_TIMER_END(GRPC_PTAG_CPP_PERFORM_OPS, call->call());
 }
 
 void* Channel::RegisterMethod(const char* method) {
   return grpc_channel_register_call(c_channel_, method,
-                                    host_.empty() ? NULL : host_.c_str());
+                                    host_.empty() ? NULL : host_.c_str(),
+                                    nullptr);
 }
 
 grpc_connectivity_state Channel::GetState(bool try_to_connect) {
diff --git a/src/cpp/client/client_context.cc b/src/cpp/client/client_context.cc
index dd86e7b108a..b8caa1eae4d 100644
--- a/src/cpp/client/client_context.cc
+++ b/src/cpp/client/client_context.cc
@@ -77,19 +77,19 @@ void ClientContext::set_call(grpc_call* call,
   channel_ = channel;
   if (creds_ && !creds_->ApplyToCall(call_)) {
     grpc_call_cancel_with_status(call, GRPC_STATUS_CANCELLED,
-                                 "Failed to set credentials to rpc.");
+                                 "Failed to set credentials to rpc.", nullptr);
   }
 }
 
 void ClientContext::set_compression_algorithm(
     grpc_compression_algorithm algorithm) {
-  char* algorithm_name = NULL;
+  char* algorithm_name = nullptr;
   if (!grpc_compression_algorithm_name(algorithm, &algorithm_name)) {
     gpr_log(GPR_ERROR, "Name for compression algorithm '%d' unknown.",
             algorithm);
     abort();
   }
-  GPR_ASSERT(algorithm_name != NULL);
+  GPR_ASSERT(algorithm_name != nullptr);
   AddMetadata(GRPC_COMPRESS_REQUEST_ALGORITHM_KEY, algorithm_name);
 }
 
@@ -102,7 +102,7 @@ std::shared_ptr<const AuthContext> ClientContext::auth_context() const {
 
 void ClientContext::TryCancel() {
   if (call_) {
-    grpc_call_cancel(call_);
+    grpc_call_cancel(call_, nullptr);
   }
 }
 
diff --git a/src/cpp/client/insecure_credentials.cc b/src/cpp/client/insecure_credentials.cc
index d8dcaa1436a..2f9357b5686 100644
--- a/src/cpp/client/insecure_credentials.cc
+++ b/src/cpp/client/insecure_credentials.cc
@@ -49,7 +49,7 @@ class InsecureCredentialsImpl GRPC_FINAL : public Credentials {
     grpc_channel_args channel_args;
     args.SetChannelArgs(&channel_args);
     return std::shared_ptr<ChannelInterface>(new Channel(
-        grpc_insecure_channel_create(target.c_str(), &channel_args)));
+        grpc_insecure_channel_create(target.c_str(), &channel_args, nullptr)));
   }
 
   // InsecureCredentials should not be applied to a call.
diff --git a/src/cpp/common/completion_queue.cc b/src/cpp/common/completion_queue.cc
index 593963f672f..fca33f8f542 100644
--- a/src/cpp/common/completion_queue.cc
+++ b/src/cpp/common/completion_queue.cc
@@ -40,7 +40,9 @@
 
 namespace grpc {
 
-CompletionQueue::CompletionQueue() { cq_ = grpc_completion_queue_create(); }
+CompletionQueue::CompletionQueue() {
+  cq_ = grpc_completion_queue_create(nullptr);
+}
 
 CompletionQueue::CompletionQueue(grpc_completion_queue* take) : cq_(take) {}
 
@@ -51,7 +53,7 @@ void CompletionQueue::Shutdown() { grpc_completion_queue_shutdown(cq_); }
 CompletionQueue::NextStatus CompletionQueue::AsyncNextInternal(
     void** tag, bool* ok, gpr_timespec deadline) {
   for (;;) {
-    auto ev = grpc_completion_queue_next(cq_, deadline);
+    auto ev = grpc_completion_queue_next(cq_, deadline, nullptr);
     switch (ev.type) {
       case GRPC_QUEUE_TIMEOUT:
         return TIMEOUT;
@@ -70,8 +72,8 @@ CompletionQueue::NextStatus CompletionQueue::AsyncNextInternal(
 }
 
 bool CompletionQueue::Pluck(CompletionQueueTag* tag) {
-  auto ev =
-      grpc_completion_queue_pluck(cq_, tag, gpr_inf_future(GPR_CLOCK_REALTIME));
+  auto deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
+  auto ev = grpc_completion_queue_pluck(cq_, tag, deadline, nullptr);
   bool ok = ev.success != 0;
   void* ignored = tag;
   GPR_ASSERT(tag->FinalizeResult(&ignored, &ok));
@@ -81,8 +83,8 @@ bool CompletionQueue::Pluck(CompletionQueueTag* tag) {
 }
 
 void CompletionQueue::TryPluck(CompletionQueueTag* tag) {
-  auto ev =
-      grpc_completion_queue_pluck(cq_, tag, gpr_time_0(GPR_CLOCK_REALTIME));
+  auto deadline = gpr_time_0(GPR_CLOCK_REALTIME);
+  auto ev = grpc_completion_queue_pluck(cq_, tag, deadline, nullptr);
   if (ev.type == GRPC_QUEUE_TIMEOUT) return;
   bool ok = ev.success != 0;
   void* ignored = tag;
diff --git a/src/cpp/server/server.cc b/src/cpp/server/server.cc
index ab87b22f5fb..da2bc946391 100644
--- a/src/cpp/server/server.cc
+++ b/src/cpp/server/server.cc
@@ -84,7 +84,7 @@ class Server::SyncRequest GRPC_FINAL : public CompletionQueueTag {
     return mrd;
   }
 
-  void SetupRequest() { cq_ = grpc_completion_queue_create(); }
+  void SetupRequest() { cq_ = grpc_completion_queue_create(nullptr); }
 
   void TeardownRequest() {
     grpc_completion_queue_destroy(cq_);
@@ -170,9 +170,9 @@ static grpc_server* CreateServer(int max_message_size) {
     arg.key = const_cast<char*>(GRPC_ARG_MAX_MESSAGE_LENGTH);
     arg.value.integer = max_message_size;
     grpc_channel_args args = {1, &arg};
-    return grpc_server_create(&args);
+    return grpc_server_create(&args, nullptr);
   } else {
-    return grpc_server_create(nullptr);
+    return grpc_server_create(nullptr, nullptr);
   }
 }
 
@@ -186,7 +186,7 @@ Server::Server(ThreadPoolInterface* thread_pool, bool thread_pool_owned,
       server_(CreateServer(max_message_size)),
       thread_pool_(thread_pool),
       thread_pool_owned_(thread_pool_owned) {
-  grpc_server_register_completion_queue(server_, cq_.cq());
+  grpc_server_register_completion_queue(server_, cq_.cq(), nullptr);
 }
 
 Server::~Server() {
@@ -297,8 +297,8 @@ void Server::PerformOpsOnCall(CallOpSetInterface* ops, Call* call) {
   size_t nops = 0;
   grpc_op cops[MAX_OPS];
   ops->FillOps(cops, &nops);
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call->call(), cops, nops, ops));
+  auto result = grpc_call_start_batch(call->call(), cops, nops, ops, nullptr);
+  GPR_ASSERT(GRPC_CALL_OK == result);
 }
 
 Server::BaseAsyncRequest::BaseAsyncRequest(
diff --git a/src/cpp/server/server_builder.cc b/src/cpp/server/server_builder.cc
index f723d4611ae..ce7682e8a77 100644
--- a/src/cpp/server/server_builder.cc
+++ b/src/cpp/server/server_builder.cc
@@ -103,7 +103,8 @@ std::unique_ptr<Server> ServerBuilder::BuildAndStart() {
   std::unique_ptr<Server> server(
       new Server(thread_pool_, thread_pool_owned, max_message_size_));
   for (auto cq = cqs_.begin(); cq != cqs_.end(); ++cq) {
-    grpc_server_register_completion_queue(server->server_, (*cq)->cq());
+    grpc_server_register_completion_queue(server->server_, (*cq)->cq(),
+                                          nullptr);
   }
   for (auto service = services_.begin(); service != services_.end();
        service++) {
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index 04373397f92..bb34040a2ff 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -91,6 +91,7 @@ void ServerContext::CompletionOp::FillOps(grpc_op* ops, size_t* nops) {
   ops->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   ops->data.recv_close_on_server.cancelled = &cancelled_;
   ops->flags = 0;
+  ops->reserved = NULL;
   *nops = 1;
 }
 
diff --git a/src/csharp/ext/grpc_csharp_ext.c b/src/csharp/ext/grpc_csharp_ext.c
index 9379ae01f14..bf2bbd873b0 100644
--- a/src/csharp/ext/grpc_csharp_ext.c
+++ b/src/csharp/ext/grpc_csharp_ext.c
@@ -339,7 +339,7 @@ GPR_EXPORT void GPR_CALLTYPE grpcsharp_shutdown(void) { grpc_shutdown(); }
 
 GPR_EXPORT grpc_completion_queue *GPR_CALLTYPE
 grpcsharp_completion_queue_create(void) {
-  return grpc_completion_queue_create();
+  return grpc_completion_queue_create(NULL);
 }
 
 GPR_EXPORT void GPR_CALLTYPE
@@ -354,13 +354,14 @@ grpcsharp_completion_queue_destroy(grpc_completion_queue *cq) {
 
 GPR_EXPORT grpc_event GPR_CALLTYPE
 grpcsharp_completion_queue_next(grpc_completion_queue *cq) {
-  return grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME));
+  return grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME),
+                                    NULL);
 }
 
 GPR_EXPORT grpc_event GPR_CALLTYPE
 grpcsharp_completion_queue_pluck(grpc_completion_queue *cq, void *tag) {
   return grpc_completion_queue_pluck(cq, tag,
-                                     gpr_inf_future(GPR_CLOCK_REALTIME));
+                                     gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
 }
 
 /* Channel */
@@ -368,7 +369,7 @@ grpcsharp_completion_queue_pluck(grpc_completion_queue *cq, void *tag) {
 GPR_EXPORT grpc_channel *GPR_CALLTYPE
 
 grpcsharp_insecure_channel_create(const char *target, const grpc_channel_args *args) {
-  return grpc_insecure_channel_create(target, args);
+  return grpc_insecure_channel_create(target, args, NULL);
 }
 
 GPR_EXPORT void GPR_CALLTYPE grpcsharp_channel_destroy(grpc_channel *channel) {
@@ -382,7 +383,7 @@ grpcsharp_channel_create_call(grpc_channel *channel, grpc_call *parent_call,
                               const char *method, const char *host,
                               gpr_timespec deadline) {
   return grpc_channel_create_call(channel, parent_call, propagation_mask, cq,
-                                  method, host, deadline);
+                                  method, host, deadline, NULL);
 }
 
 GPR_EXPORT grpc_connectivity_state GPR_CALLTYPE
@@ -475,13 +476,13 @@ GPR_EXPORT gpr_int32 GPR_CALLTYPE gprsharp_sizeof_timespec(void) {
 /* Call */
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_cancel(grpc_call *call) {
-  return grpc_call_cancel(call);
+  return grpc_call_cancel(call, NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
 grpcsharp_call_cancel_with_status(grpc_call *call, grpc_status_code status,
                                   const char *description) {
-  return grpc_call_cancel_with_status(call, status, description);
+  return grpc_call_cancel_with_status(call, status, description, NULL);
 }
 
 GPR_EXPORT char *GPR_CALLTYPE grpcsharp_call_get_peer(grpc_call *call) {
@@ -538,7 +539,8 @@ grpcsharp_call_start_unary(grpc_call *call, grpcsharp_batch_context *ctx,
       &(ctx->recv_status_on_client.status_details_capacity);
   ops[5].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+                               NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -575,7 +577,8 @@ grpcsharp_call_start_client_streaming(grpc_call *call,
       &(ctx->recv_status_on_client.status_details_capacity);
   ops[3].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+                               NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_start_server_streaming(
@@ -615,7 +618,8 @@ GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_start_server_streaming(
       &(ctx->recv_status_on_client.status_details_capacity);
   ops[4].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+                               NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -648,7 +652,8 @@ grpcsharp_call_start_duplex_streaming(grpc_call *call,
       &(ctx->recv_status_on_client.status_details_capacity);
   ops[2].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+                               NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -668,7 +673,7 @@ grpcsharp_call_send_message(grpc_call *call, grpcsharp_batch_context *ctx,
   ops[1].data.send_initial_metadata.metadata = NULL;
   ops[1].flags = 0;
 
-  return grpc_call_start_batch(call, ops, nops, ctx);
+  return grpc_call_start_batch(call, ops, nops, ctx, NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -679,7 +684,8 @@ grpcsharp_call_send_close_from_client(grpc_call *call,
   ops[0].op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   ops[0].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+                               NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_send_status_from_server(
@@ -705,7 +711,7 @@ GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_send_status_from_server(
   ops[1].data.send_initial_metadata.metadata = NULL;
   ops[1].flags = 0;
 
-  return grpc_call_start_batch(call, ops, nops, ctx);
+  return grpc_call_start_batch(call, ops, nops, ctx, NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -715,7 +721,8 @@ grpcsharp_call_recv_message(grpc_call *call, grpcsharp_batch_context *ctx) {
   ops[0].op = GRPC_OP_RECV_MESSAGE;
   ops[0].data.recv_message = &(ctx->recv_message);
   ops[0].flags = 0;
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+                               NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -727,7 +734,8 @@ grpcsharp_call_start_serverside(grpc_call *call, grpcsharp_batch_context *ctx) {
       (&ctx->recv_close_on_server_cancelled);
   ops[0].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+                               NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -744,7 +752,8 @@ grpcsharp_call_send_initial_metadata(grpc_call *call,
       ctx->send_initial_metadata.metadata;
   ops[0].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+                               NULL);
 }
 
 /* Server */
@@ -752,8 +761,8 @@ grpcsharp_call_send_initial_metadata(grpc_call *call,
 GPR_EXPORT grpc_server *GPR_CALLTYPE
 grpcsharp_server_create(grpc_completion_queue *cq,
                         const grpc_channel_args *args) {
-  grpc_server *server = grpc_server_create(args);
-  grpc_server_register_completion_queue(server, cq);
+  grpc_server *server = grpc_server_create(args, NULL);
+  grpc_server_register_completion_queue(server, cq, NULL);
   return server;
 }
 
diff --git a/src/node/ext/call.cc b/src/node/ext/call.cc
index c5c83133850..6fc1bc424f1 100644
--- a/src/node/ext/call.cc
+++ b/src/node/ext/call.cc
@@ -516,12 +516,12 @@ NAN_METHOD(Call::New) {
         wrapped_call = grpc_channel_create_call(
             wrapped_channel, NULL, GRPC_PROPAGATE_DEFAULTS,
             CompletionQueueAsyncWorker::GetQueue(), *method,
-            *host_override, MillisecondsToTimespec(deadline));
+            *host_override, MillisecondsToTimespec(deadline), NULL);
       } else if (args[3]->IsUndefined() || args[3]->IsNull()) {
         wrapped_call = grpc_channel_create_call(
             wrapped_channel, NULL, GRPC_PROPAGATE_DEFAULTS,
             CompletionQueueAsyncWorker::GetQueue(), *method,
-            NULL, MillisecondsToTimespec(deadline));
+            NULL, MillisecondsToTimespec(deadline), NULL);
       } else {
         return NanThrowTypeError("Call's fourth argument must be a string");
       }
@@ -601,7 +601,7 @@ NAN_METHOD(Call::StartBatch) {
   NanCallback *callback = new NanCallback(callback_func);
   grpc_call_error error = grpc_call_start_batch(
       call->wrapped_call, &ops[0], nops, new struct tag(
-          callback, op_vector.release(), resources));
+          callback, op_vector.release(), resources), NULL);
   if (error != GRPC_CALL_OK) {
     return NanThrowError("startBatch failed", error);
   }
@@ -615,7 +615,7 @@ NAN_METHOD(Call::Cancel) {
     return NanThrowTypeError("cancel can only be called on Call objects");
   }
   Call *call = ObjectWrap::Unwrap<Call>(args.This());
-  grpc_call_error error = grpc_call_cancel(call->wrapped_call);
+  grpc_call_error error = grpc_call_cancel(call->wrapped_call, NULL);
   if (error != GRPC_CALL_OK) {
     return NanThrowError("cancel failed", error);
   }
diff --git a/src/node/ext/channel.cc b/src/node/ext/channel.cc
index 457a58c0577..45d0d09e228 100644
--- a/src/node/ext/channel.cc
+++ b/src/node/ext/channel.cc
@@ -111,7 +111,7 @@ NAN_METHOD(Channel::New) {
     grpc_channel_args *channel_args_ptr;
     if (args[2]->IsUndefined()) {
       channel_args_ptr = NULL;
-      wrapped_channel = grpc_insecure_channel_create(*host, NULL);
+      wrapped_channel = grpc_insecure_channel_create(*host, NULL, NULL);
     } else if (args[2]->IsObject()) {
       Handle<Object> args_hash(args[2]->ToObject()->Clone());
       Handle<Array> keys(args_hash->GetOwnPropertyNames());
@@ -145,7 +145,8 @@ NAN_METHOD(Channel::New) {
       return NanThrowTypeError("Channel expects a string and an object");
     }
     if (creds == NULL) {
-      wrapped_channel = grpc_insecure_channel_create(*host, channel_args_ptr);
+      wrapped_channel = grpc_insecure_channel_create(*host, channel_args_ptr,
+                                                     NULL);
     } else {
       wrapped_channel =
           grpc_secure_channel_create(creds, *host, channel_args_ptr);
diff --git a/src/node/ext/completion_queue_async_worker.cc b/src/node/ext/completion_queue_async_worker.cc
index 1215c97e193..4501e848ae3 100644
--- a/src/node/ext/completion_queue_async_worker.cc
+++ b/src/node/ext/completion_queue_async_worker.cc
@@ -63,7 +63,7 @@ CompletionQueueAsyncWorker::~CompletionQueueAsyncWorker() {}
 
 void CompletionQueueAsyncWorker::Execute() {
   result =
-      grpc_completion_queue_next(queue, gpr_inf_future(GPR_CLOCK_REALTIME));
+      grpc_completion_queue_next(queue, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   if (!result.success) {
     SetErrorMessage("The batch encountered an error");
   }
@@ -85,7 +85,7 @@ void CompletionQueueAsyncWorker::Init(Handle<Object> exports) {
   NanScope();
   current_threads = 0;
   waiting_next_calls = 0;
-  queue = grpc_completion_queue_create();
+  queue = grpc_completion_queue_create(NULL);
 }
 
 void CompletionQueueAsyncWorker::HandleOKCallback() {
diff --git a/src/node/ext/server.cc b/src/node/ext/server.cc
index 1dc179db3d7..8e39644846d 100644
--- a/src/node/ext/server.cc
+++ b/src/node/ext/server.cc
@@ -113,8 +113,8 @@ class NewCallOp : public Op {
 };
 
 Server::Server(grpc_server *server) : wrapped_server(server) {
-  shutdown_queue = grpc_completion_queue_create();
-  grpc_server_register_completion_queue(server, shutdown_queue);
+  shutdown_queue = grpc_completion_queue_create(NULL);
+  grpc_server_register_completion_queue(server, shutdown_queue, NULL);
 }
 
 Server::~Server() {
@@ -158,7 +158,7 @@ void Server::ShutdownServer() {
                                     this->shutdown_queue,
                                     NULL);
     grpc_completion_queue_pluck(this->shutdown_queue, NULL,
-                                gpr_inf_future(GPR_CLOCK_REALTIME));
+                                gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
     this->wrapped_server = NULL;
   }
 }
@@ -176,7 +176,7 @@ NAN_METHOD(Server::New) {
   grpc_server *wrapped_server;
   grpc_completion_queue *queue = CompletionQueueAsyncWorker::GetQueue();
   if (args[0]->IsUndefined()) {
-    wrapped_server = grpc_server_create(NULL);
+    wrapped_server = grpc_server_create(NULL, NULL);
   } else if (args[0]->IsObject()) {
     Handle<Object> args_hash(args[0]->ToObject());
     Handle<Array> keys(args_hash->GetOwnPropertyNames());
@@ -205,12 +205,12 @@ NAN_METHOD(Server::New) {
         return NanThrowTypeError("Arg values must be strings");
       }
     }
-    wrapped_server = grpc_server_create(&channel_args);
+    wrapped_server = grpc_server_create(&channel_args, NULL);
     free(channel_args.args);
   } else {
     return NanThrowTypeError("Server expects an object");
   }
-  grpc_server_register_completion_queue(wrapped_server, queue);
+  grpc_server_register_completion_queue(wrapped_server, queue, NULL);
   Server *server = new Server(wrapped_server);
   server->Wrap(args.This());
   NanReturnValue(args.This());
diff --git a/src/objective-c/GRPCClient/private/GRPCCompletionQueue.m b/src/objective-c/GRPCClient/private/GRPCCompletionQueue.m
index 696069c200f..ea2b01ee1d7 100644
--- a/src/objective-c/GRPCClient/private/GRPCCompletionQueue.m
+++ b/src/objective-c/GRPCClient/private/GRPCCompletionQueue.m
@@ -43,7 +43,7 @@
 
 - (instancetype)init {
   if ((self = [super init])) {
-    _unmanagedQueue = grpc_completion_queue_create();
+    _unmanagedQueue = grpc_completion_queue_create(NULL);
 
     // This is for the following block to capture the pointer by value (instead
     // of retaining self and doing self->_unmanagedQueue). This is essential
@@ -64,7 +64,8 @@
       while (YES) {
         // The following call blocks until an event is available.
         grpc_event event = grpc_completion_queue_next(unmanagedQueue,
-                                                      gpr_inf_future(GPR_CLOCK_REALTIME));
+                                                      gpr_inf_future(GPR_CLOCK_REALTIME),
+                                                      NULL);
         GRPCQueueCompletionHandler handler;
         switch (event.type) {
           case GRPC_OP_COMPLETE:
diff --git a/src/objective-c/GRPCClient/private/GRPCHost.m b/src/objective-c/GRPCClient/private/GRPCHost.m
index d902f95b516..a7142d0f009 100644
--- a/src/objective-c/GRPCClient/private/GRPCHost.m
+++ b/src/objective-c/GRPCClient/private/GRPCHost.m
@@ -97,7 +97,7 @@
                                   queue.unmanagedQueue,
                                   path.UTF8String,
                                   self.hostName.UTF8String,
-                                  gpr_inf_future(GPR_CLOCK_REALTIME));
+                                  gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
 }
 
 - (GRPCChannel *)channel {
diff --git a/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.m b/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.m
index 070a529629a..15b6ffc75cf 100644
--- a/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.m
+++ b/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.m
@@ -38,7 +38,7 @@
 @implementation GRPCUnsecuredChannel
 
 - (instancetype)initWithHost:(NSString *)host {
-  return (self = [super initWithChannel:grpc_insecure_channel_create(host.UTF8String, NULL)]);
+  return (self = [super initWithChannel:grpc_insecure_channel_create(host.UTF8String, NULL, NULL)]);
 }
 
 // TODO(jcanizales): GRPCSecureChannel and GRPCUnsecuredChannel are just convenience initializers
diff --git a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
index 951c0510369..fe3d51da53a 100644
--- a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
+++ b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
@@ -282,7 +282,7 @@
     for (GRPCOperation *operation in operations) {
       [operation finish];
     }
-  }));
+  }), NULL);
   gpr_free(ops_array);
 
   if (error != GRPC_CALL_OK) {
@@ -293,7 +293,7 @@
 }
 
 - (void)cancel {
-  grpc_call_cancel(_call);
+  grpc_call_cancel(_call, NULL);
 }
 
 - (void)dealloc {
diff --git a/src/php/ext/grpc/call.c b/src/php/ext/grpc/call.c
index 01ec909b792..1cf766c3120 100644
--- a/src/php/ext/grpc/call.c
+++ b/src/php/ext/grpc/call.c
@@ -241,7 +241,7 @@ PHP_METHOD(Call, __construct) {
           deadline_obj TSRMLS_CC);
   call->wrapped = grpc_channel_create_call(
       channel->wrapped, NULL, GRPC_PROPAGATE_DEFAULTS, completion_queue, method,
-      channel->target, deadline->wrapped);
+      channel->target, deadline->wrapped, NULL);
 }
 
 /**
@@ -400,7 +400,8 @@ PHP_METHOD(Call, startBatch) {
     ops[op_num].flags = 0;
     op_num++;
   }
-  error = grpc_call_start_batch(call->wrapped, ops, op_num, call->wrapped);
+  error = grpc_call_start_batch(call->wrapped, ops, op_num, call->wrapped,
+                                NULL);
   if (error != GRPC_CALL_OK) {
     zend_throw_exception(spl_ce_LogicException,
                          "start_batch was called incorrectly",
@@ -408,7 +409,7 @@ PHP_METHOD(Call, startBatch) {
     goto cleanup;
   }
   event = grpc_completion_queue_pluck(completion_queue, call->wrapped,
-                                      gpr_inf_future(GPR_CLOCK_REALTIME));
+                                      gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   if (!event.success) {
     zend_throw_exception(spl_ce_LogicException,
                          "The batch failed for some reason",
@@ -489,7 +490,7 @@ PHP_METHOD(Call, getPeer) {
 PHP_METHOD(Call, cancel) {
   wrapped_grpc_call *call =
       (wrapped_grpc_call *)zend_object_store_get_object(getThis() TSRMLS_CC);
-  grpc_call_cancel(call->wrapped);
+  grpc_call_cancel(call->wrapped, NULL);
 }
 
 static zend_function_entry call_methods[] = {
diff --git a/src/php/ext/grpc/channel.c b/src/php/ext/grpc/channel.c
index 447cfc15bee..f8ce04d9023 100644
--- a/src/php/ext/grpc/channel.c
+++ b/src/php/ext/grpc/channel.c
@@ -154,7 +154,7 @@ PHP_METHOD(Channel, __construct) {
   override = target;
   override_len = target_length;
   if (args_array == NULL) {
-    channel->wrapped = grpc_insecure_channel_create(target, NULL);
+    channel->wrapped = grpc_insecure_channel_create(target, NULL, NULL);
   } else {
     array_hash = Z_ARRVAL_P(args_array);
     if (zend_hash_find(array_hash, "credentials", sizeof("credentials"),
@@ -184,7 +184,7 @@ PHP_METHOD(Channel, __construct) {
     }
     php_grpc_read_args_array(args_array, &args);
     if (creds == NULL) {
-      channel->wrapped = grpc_insecure_channel_create(target, &args);
+      channel->wrapped = grpc_insecure_channel_create(target, &args, NULL);
     } else {
       gpr_log(GPR_DEBUG, "Initialized secure channel");
       channel->wrapped =
@@ -255,7 +255,7 @@ PHP_METHOD(Channel, watchConnectivityState) {
       deadline->wrapped, completion_queue, NULL);
   grpc_event event = grpc_completion_queue_pluck(
       completion_queue, NULL,
-      gpr_inf_future(GPR_CLOCK_REALTIME));
+      gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   RETURN_BOOL(event.success);
 }
 
diff --git a/src/php/ext/grpc/completion_queue.c b/src/php/ext/grpc/completion_queue.c
index c653a592efd..741204b0b10 100644
--- a/src/php/ext/grpc/completion_queue.c
+++ b/src/php/ext/grpc/completion_queue.c
@@ -38,14 +38,13 @@
 grpc_completion_queue *completion_queue;
 
 void grpc_php_init_completion_queue(TSRMLS_D) {
-  completion_queue = grpc_completion_queue_create();
+  completion_queue = grpc_completion_queue_create(NULL);
 }
 
 void grpc_php_shutdown_completion_queue(TSRMLS_D) {
   grpc_completion_queue_shutdown(completion_queue);
   while (grpc_completion_queue_next(completion_queue,
-                                    gpr_inf_future(GPR_CLOCK_REALTIME))
-             .type != GRPC_QUEUE_SHUTDOWN)
-    ;
+                                    gpr_inf_future(GPR_CLOCK_REALTIME),
+                                    NULL).type != GRPC_QUEUE_SHUTDOWN);
   grpc_completion_queue_destroy(completion_queue);
 }
diff --git a/src/php/ext/grpc/server.c b/src/php/ext/grpc/server.c
index d58aa884ca8..ca129e76ca1 100644
--- a/src/php/ext/grpc/server.c
+++ b/src/php/ext/grpc/server.c
@@ -66,7 +66,7 @@ void free_wrapped_grpc_server(void *object TSRMLS_DC) {
     grpc_server_shutdown_and_notify(server->wrapped, completion_queue, NULL);
     grpc_server_cancel_all_calls(server->wrapped);
     grpc_completion_queue_pluck(completion_queue, NULL,
-                                gpr_inf_future(GPR_CLOCK_REALTIME));
+                                gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
     grpc_server_destroy(server->wrapped);
   }
   efree(server);
@@ -109,13 +109,14 @@ PHP_METHOD(Server, __construct) {
     return;
   }
   if (args_array == NULL) {
-    server->wrapped = grpc_server_create(NULL);
+    server->wrapped = grpc_server_create(NULL, NULL);
   } else {
     php_grpc_read_args_array(args_array, &args);
-    server->wrapped = grpc_server_create(&args);
+    server->wrapped = grpc_server_create(&args, NULL);
     efree(args.args);
   }
-  grpc_server_register_completion_queue(server->wrapped, completion_queue);
+  grpc_server_register_completion_queue(server->wrapped, completion_queue,
+                                        NULL);
 }
 
 /**
@@ -146,7 +147,7 @@ PHP_METHOD(Server, requestCall) {
     goto cleanup;
   }
   event = grpc_completion_queue_pluck(completion_queue, NULL,
-                                      gpr_inf_future(GPR_CLOCK_REALTIME));
+                                      gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   if (!event.success) {
     zend_throw_exception(spl_ce_LogicException,
                          "Failed to request a call for some reason",
diff --git a/src/python/grpcio/grpc/_adapter/_c/types/call.c b/src/python/grpcio/grpc/_adapter/_c/types/call.c
index 5e46605c450..42a50151f60 100644
--- a/src/python/grpcio/grpc/_adapter/_c/types/call.c
+++ b/src/python/grpcio/grpc/_adapter/_c/types/call.c
@@ -132,7 +132,7 @@ PyObject *pygrpc_Call_start_batch(Call *self, PyObject *args, PyObject *kwargs)
     }
   }
   tag = pygrpc_produce_batch_tag(user_tag, self, ops, nops);
-  errcode = grpc_call_start_batch(self->c_call, tag->ops, tag->nops, tag);
+  errcode = grpc_call_start_batch(self->c_call, tag->ops, tag->nops, tag, NULL);
   gpr_free(ops);
   return PyInt_FromLong(errcode);
 }
@@ -152,13 +152,13 @@ PyObject *pygrpc_Call_cancel(Call *self, PyObject *args, PyObject *kwargs) {
       return NULL;
     }
     code = PyInt_AsLong(py_code);
-    errcode = grpc_call_cancel_with_status(self->c_call, code, details);
+    errcode = grpc_call_cancel_with_status(self->c_call, code, details, NULL);
   } else if (py_code != NULL || details != NULL) {
     PyErr_SetString(PyExc_ValueError,
                     "if `code` is specified, so must `details`");
     return NULL;
   } else {
-    errcode = grpc_call_cancel(self->c_call);
+    errcode = grpc_call_cancel(self->c_call, NULL);
   }
   return PyInt_FromLong(errcode);
 }
diff --git a/src/python/grpcio/grpc/_adapter/_c/types/channel.c b/src/python/grpcio/grpc/_adapter/_c/types/channel.c
index eb9d43d1540..c577ac05eb0 100644
--- a/src/python/grpcio/grpc/_adapter/_c/types/channel.c
+++ b/src/python/grpcio/grpc/_adapter/_c/types/channel.c
@@ -108,7 +108,7 @@ Channel *pygrpc_Channel_new(
   if (creds) {
     self->c_chan = grpc_secure_channel_create(creds->c_creds, target, &c_args);
   } else {
-    self->c_chan = grpc_insecure_channel_create(target, &c_args);
+    self->c_chan = grpc_insecure_channel_create(target, &c_args, NULL);
   }
   pygrpc_discard_channel_args(c_args);
   return self;
@@ -133,7 +133,7 @@ Call *pygrpc_Channel_create_call(
   call = pygrpc_Call_new_empty(cq);
   call->c_call = grpc_channel_create_call(
       self->c_chan, NULL, GRPC_PROPAGATE_DEFAULTS, cq->c_cq, method, host,
-      pygrpc_cast_double_to_gpr_timespec(deadline));
+      pygrpc_cast_double_to_gpr_timespec(deadline), NULL);
   return call;
 }
 
diff --git a/src/python/grpcio/grpc/_adapter/_c/types/completion_queue.c b/src/python/grpcio/grpc/_adapter/_c/types/completion_queue.c
index 2dd44b6ddd8..d8bb89ca4bc 100644
--- a/src/python/grpcio/grpc/_adapter/_c/types/completion_queue.c
+++ b/src/python/grpcio/grpc/_adapter/_c/types/completion_queue.c
@@ -90,7 +90,7 @@ PyTypeObject pygrpc_CompletionQueue_type = {
 CompletionQueue *pygrpc_CompletionQueue_new(
     PyTypeObject *type, PyObject *args, PyObject *kwargs) {
   CompletionQueue *self = (CompletionQueue *)type->tp_alloc(type, 0);
-  self->c_cq = grpc_completion_queue_create();
+  self->c_cq = grpc_completion_queue_create(NULL);
   return self;
 }
 
@@ -111,7 +111,7 @@ PyObject *pygrpc_CompletionQueue_next(
   }
   Py_BEGIN_ALLOW_THREADS;
   event = grpc_completion_queue_next(
-      self->c_cq, pygrpc_cast_double_to_gpr_timespec(deadline));
+      self->c_cq, pygrpc_cast_double_to_gpr_timespec(deadline), NULL);
   Py_END_ALLOW_THREADS;
   transliterated_event = pygrpc_consume_event(event);
   return transliterated_event;
diff --git a/src/python/grpcio/grpc/_adapter/_c/types/server.c b/src/python/grpcio/grpc/_adapter/_c/types/server.c
index 2a11d09d218..15c98f28eb5 100644
--- a/src/python/grpcio/grpc/_adapter/_c/types/server.c
+++ b/src/python/grpcio/grpc/_adapter/_c/types/server.c
@@ -104,8 +104,8 @@ Server *pygrpc_Server_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
     return NULL;
   }
   self = (Server *)type->tp_alloc(type, 0);
-  self->c_serv = grpc_server_create(&c_args);
-  grpc_server_register_completion_queue(self->c_serv, cq->c_cq);
+  self->c_serv = grpc_server_create(&c_args, NULL);
+  grpc_server_register_completion_queue(self->c_serv, cq->c_cq, NULL);
   pygrpc_discard_channel_args(c_args);
   self->cq = cq;
   Py_INCREF(self->cq);
diff --git a/src/ruby/ext/grpc/rb_call.c b/src/ruby/ext/grpc/rb_call.c
index 88659da5354..70f0795f29e 100644
--- a/src/ruby/ext/grpc/rb_call.c
+++ b/src/ruby/ext/grpc/rb_call.c
@@ -170,7 +170,7 @@ static VALUE grpc_rb_call_cancel(VALUE self) {
   grpc_call *call = NULL;
   grpc_call_error err;
   TypedData_Get_Struct(self, grpc_call, &grpc_call_data_type, call);
-  err = grpc_call_cancel(call);
+  err = grpc_call_cancel(call, NULL);
   if (err != GRPC_CALL_OK) {
     rb_raise(grpc_rb_eCallError, "cancel failed: %s (code=%d)",
              grpc_call_error_detail_of(err), err);
@@ -615,7 +615,7 @@ static VALUE grpc_rb_call_run_batch(VALUE self, VALUE cqueue, VALUE tag,
 
   /* call grpc_call_start_batch, then wait for it to complete using
    * pluck_event */
-  err = grpc_call_start_batch(call, st.ops, st.op_num, ROBJECT(tag));
+  err = grpc_call_start_batch(call, st.ops, st.op_num, ROBJECT(tag), NULL);
   if (err != GRPC_CALL_OK) {
     grpc_run_batch_stack_cleanup(&st);
     rb_raise(grpc_rb_eCallError,
diff --git a/src/ruby/ext/grpc/rb_channel.c b/src/ruby/ext/grpc/rb_channel.c
index 2129ba34858..6491aa4fb4b 100644
--- a/src/ruby/ext/grpc/rb_channel.c
+++ b/src/ruby/ext/grpc/rb_channel.c
@@ -147,7 +147,7 @@ static VALUE grpc_rb_channel_init(int argc, VALUE *argv, VALUE self) {
   target_chars = StringValueCStr(target);
   grpc_rb_hash_convert_to_channel_args(channel_args, &args);
   if (credentials == Qnil) {
-    ch = grpc_insecure_channel_create(target_chars, &args);
+    ch = grpc_insecure_channel_create(target_chars, &args, NULL);
   } else {
     creds = grpc_rb_get_wrapped_credentials(credentials);
     ch = grpc_secure_channel_create(creds, target_chars, &args);
@@ -288,7 +288,7 @@ static VALUE grpc_rb_channel_create_call(VALUE self, VALUE cqueue,
   call = grpc_channel_create_call(ch, parent_call, flags, cq, method_chars,
                                   host_chars, grpc_rb_time_timeval(
                                       deadline,
-                                      /* absolute time */ 0));
+                                      /* absolute time */ 0), NULL);
   if (call == NULL) {
     rb_raise(rb_eRuntimeError, "cannot create call with method %s",
              method_chars);
diff --git a/src/ruby/ext/grpc/rb_completion_queue.c b/src/ruby/ext/grpc/rb_completion_queue.c
index b6674d76824..0bc9eb2a97a 100644
--- a/src/ruby/ext/grpc/rb_completion_queue.c
+++ b/src/ruby/ext/grpc/rb_completion_queue.c
@@ -56,7 +56,7 @@ typedef struct next_call_stack {
 static void *grpc_rb_completion_queue_next_no_gil(void *param) {
   next_call_stack *const next_call = (next_call_stack*)param;
   next_call->event =
-      grpc_completion_queue_next(next_call->cq, next_call->timeout);
+      grpc_completion_queue_next(next_call->cq, next_call->timeout, NULL);
   return NULL;
 }
 
@@ -64,7 +64,7 @@ static void *grpc_rb_completion_queue_next_no_gil(void *param) {
 static void *grpc_rb_completion_queue_pluck_no_gil(void *param) {
   next_call_stack *const next_call = (next_call_stack*)param;
   next_call->event = grpc_completion_queue_pluck(next_call->cq, next_call->tag,
-                                                 next_call->timeout);
+                                                 next_call->timeout, NULL);
   return NULL;
 }
 
@@ -128,7 +128,7 @@ static rb_data_type_t grpc_rb_completion_queue_data_type = {
 
 /* Allocates a completion queue. */
 static VALUE grpc_rb_completion_queue_alloc(VALUE cls) {
-  grpc_completion_queue *cq = grpc_completion_queue_create();
+  grpc_completion_queue *cq = grpc_completion_queue_create(NULL);
   if (cq == NULL) {
     rb_raise(rb_eArgError, "could not create a completion queue: not sure why");
   }
diff --git a/src/ruby/ext/grpc/rb_server.c b/src/ruby/ext/grpc/rb_server.c
index 79a4ae8757b..7e76349d2e1 100644
--- a/src/ruby/ext/grpc/rb_server.c
+++ b/src/ruby/ext/grpc/rb_server.c
@@ -128,7 +128,7 @@ static VALUE grpc_rb_server_init(VALUE self, VALUE cqueue, VALUE channel_args) {
   TypedData_Get_Struct(self, grpc_rb_server, &grpc_rb_server_data_type,
                        wrapper);
   grpc_rb_hash_convert_to_channel_args(channel_args, &args);
-  srv = grpc_server_create(&args);
+  srv = grpc_server_create(&args, NULL);
 
   if (args.args != NULL) {
     xfree(args.args); /* Allocated by grpc_rb_hash_convert_to_channel_args */
@@ -136,7 +136,7 @@ static VALUE grpc_rb_server_init(VALUE self, VALUE cqueue, VALUE channel_args) {
   if (srv == NULL) {
     rb_raise(rb_eRuntimeError, "could not create a gRPC server, not sure why");
   }
-  grpc_server_register_completion_queue(srv, cq);
+  grpc_server_register_completion_queue(srv, cq, NULL);
   wrapper->wrapped = srv;
 
   /* Add the cq as the server's mark object. This ensures the ruby cq can't be
diff --git a/test/core/bad_client/bad_client.c b/test/core/bad_client/bad_client.c
index b050227b61e..f7399770dd2 100644
--- a/test/core/bad_client/bad_client.c
+++ b/test/core/bad_client/bad_client.c
@@ -102,11 +102,11 @@ void grpc_run_bad_client_test(grpc_bad_client_server_side_validator validator,
 
   /* Create server, completion events */
   a.server = grpc_server_create_from_filters(NULL, 0, NULL);
-  a.cq = grpc_completion_queue_create();
+  a.cq = grpc_completion_queue_create(NULL);
   gpr_event_init(&a.done_thd);
   gpr_event_init(&a.done_write);
   a.validator = validator;
-  grpc_server_register_completion_queue(a.server, a.cq);
+  grpc_server_register_completion_queue(a.server, a.cq, NULL);
   grpc_server_start(a.server);
   transport = grpc_create_chttp2_transport(NULL, sfd.server, mdctx, 0);
   server_setup_transport(&a, transport, mdctx);
@@ -151,7 +151,8 @@ void grpc_run_bad_client_test(grpc_bad_client_server_side_validator validator,
   }
   grpc_server_shutdown_and_notify(a.server, a.cq, NULL);
   GPR_ASSERT(grpc_completion_queue_pluck(a.cq, NULL,
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(1))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(1),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(a.server);
   grpc_completion_queue_destroy(a.cq);
diff --git a/test/core/bad_client/tests/connection_prefix.c b/test/core/bad_client/tests/connection_prefix.c
index 0bd86ecf55a..de62e923f02 100644
--- a/test/core/bad_client/tests/connection_prefix.c
+++ b/test/core/bad_client/tests/connection_prefix.c
@@ -37,8 +37,8 @@
 static void verifier(grpc_server *server, grpc_completion_queue *cq) {
   while (grpc_server_has_open_connections(server)) {
     GPR_ASSERT(
-        grpc_completion_queue_next(cq, GRPC_TIMEOUT_MILLIS_TO_DEADLINE(20))
-            .type == GRPC_QUEUE_TIMEOUT);
+        grpc_completion_queue_next(cq, GRPC_TIMEOUT_MILLIS_TO_DEADLINE(20),
+                                   NULL).type == GRPC_QUEUE_TIMEOUT);
   }
 }
 
diff --git a/test/core/bad_client/tests/initial_settings_frame.c b/test/core/bad_client/tests/initial_settings_frame.c
index 2075602e276..28e9a39dff1 100644
--- a/test/core/bad_client/tests/initial_settings_frame.c
+++ b/test/core/bad_client/tests/initial_settings_frame.c
@@ -39,8 +39,8 @@
 static void verifier(grpc_server *server, grpc_completion_queue *cq) {
   while (grpc_server_has_open_connections(server)) {
     GPR_ASSERT(
-        grpc_completion_queue_next(cq, GRPC_TIMEOUT_MILLIS_TO_DEADLINE(20))
-            .type == GRPC_QUEUE_TIMEOUT);
+        grpc_completion_queue_next(cq, GRPC_TIMEOUT_MILLIS_TO_DEADLINE(20),
+                                   NULL).type == GRPC_QUEUE_TIMEOUT);
   }
 }
 
diff --git a/test/core/end2end/cq_verifier.c b/test/core/end2end/cq_verifier.c
index c28932c52b4..a9ba78dfdb3 100644
--- a/test/core/end2end/cq_verifier.c
+++ b/test/core/end2end/cq_verifier.c
@@ -226,7 +226,7 @@ void cq_verify(cq_verifier *v) {
   gpr_strvec_init(&have_tags);
 
   while (v->expect.next != &v->expect) {
-    ev = grpc_completion_queue_next(v->cq, deadline);
+    ev = grpc_completion_queue_next(v->cq, deadline, NULL);
     if (ev.type == GRPC_QUEUE_TIMEOUT) {
       fail_no_event_received(v);
       break;
@@ -265,7 +265,7 @@ void cq_verify_empty(cq_verifier *v) {
 
   GPR_ASSERT(v->expect.next == &v->expect && "expectation queue must be empty");
 
-  ev = grpc_completion_queue_next(v->cq, deadline);
+  ev = grpc_completion_queue_next(v->cq, deadline, NULL);
   if (ev.type != GRPC_QUEUE_TIMEOUT) {
     char *s = grpc_event_string(&ev);
     gpr_log(GPR_ERROR, "unexpected event (expected nothing): %s", s);
diff --git a/test/core/end2end/dualstack_socket_test.c b/test/core/end2end/dualstack_socket_test.c
index 48a88be5255..7b7dbc7472c 100644
--- a/test/core/end2end/dualstack_socket_test.c
+++ b/test/core/end2end/dualstack_socket_test.c
@@ -53,7 +53,7 @@ static gpr_timespec ms_from_now(int ms) {
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, ms_from_now(5000));
+    ev = grpc_completion_queue_next(cq, ms_from_now(5000), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -75,6 +75,7 @@ void test_connect(const char *server_host, const char *client_host, int port,
   grpc_metadata_array trailing_metadata_recv;
   grpc_metadata_array request_metadata_recv;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
@@ -93,9 +94,9 @@ void test_connect(const char *server_host, const char *client_host, int port,
   grpc_call_details_init(&call_details);
 
   /* Create server. */
-  cq = grpc_completion_queue_create();
-  server = grpc_server_create(NULL);
-  grpc_server_register_completion_queue(server, cq);
+  cq = grpc_completion_queue_create(NULL);
+  server = grpc_server_create(NULL, NULL);
+  grpc_server_register_completion_queue(server, cq, NULL);
   GPR_ASSERT((got_port = grpc_server_add_insecure_http2_port(
                   server, server_hostport)) > 0);
   if (port == 0) {
@@ -113,7 +114,7 @@ void test_connect(const char *server_host, const char *client_host, int port,
   } else {
     gpr_join_host_port(&client_hostport, client_host, port);
   }
-  client = grpc_insecure_channel_create(client_hostport, NULL);
+  client = grpc_insecure_channel_create(client_hostport, NULL, NULL);
 
   gpr_log(GPR_INFO, "Testing with server=%s client=%s (expecting %s)",
           server_hostport, client_hostport, expect_ok ? "success" : "failure");
@@ -132,20 +133,23 @@ void test_connect(const char *server_host, const char *client_host, int port,
 
   /* Send a trivial request. */
   c = grpc_channel_create_call(client, NULL, GRPC_PROPAGATE_DEFAULTS, cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -153,14 +157,16 @@ void test_connect(const char *server_host, const char *client_host, int port,
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   if (expect_ok) {
     /* Check for a successful request. */
-    GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                   server, &s, &call_details,
-                                   &request_metadata_recv, cq, cq, tag(101)));
+    error = grpc_server_request_call(server, &s, &call_details,
+                                     &request_metadata_recv, cq, cq, tag(101));
+    GPR_ASSERT(GRPC_CALL_OK == error);
     cq_expect_completion(cqv, tag(101), 1);
     cq_verify(cqv);
 
@@ -179,8 +185,8 @@ void test_connect(const char *server_host, const char *client_host, int port,
     op->data.recv_close_on_server.cancelled = &was_cancelled;
     op->flags = 0;
     op++;
-    GPR_ASSERT(GRPC_CALL_OK ==
-               grpc_call_start_batch(s, ops, op - ops, tag(102)));
+    error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+    GPR_ASSERT(GRPC_CALL_OK == error);
 
     cq_expect_completion(cqv, tag(102), 1);
     cq_expect_completion(cqv, tag(1), 1);
@@ -215,7 +221,8 @@ void test_connect(const char *server_host, const char *client_host, int port,
   /* Destroy server. */
   grpc_server_shutdown_and_notify(server, cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(server);
   grpc_completion_queue_shutdown(cq);
diff --git a/test/core/end2end/fixtures/chttp2_fake_security.c b/test/core/end2end/fixtures/chttp2_fake_security.c
index 78b692a45dd..27531ecbc3b 100644
--- a/test/core/end2end/fixtures/chttp2_fake_security.c
+++ b/test/core/end2end/fixtures/chttp2_fake_security.c
@@ -60,7 +60,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_secure_fullstack(
   gpr_join_host_port(&ffd->localaddr, "localhost", port);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -89,8 +89,8 @@ static void chttp2_init_server_secure_fullstack(
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_secure_http2_port(f->server, ffd->localaddr,
                                                server_creds));
   grpc_server_credentials_release(server_creds);
diff --git a/test/core/end2end/fixtures/chttp2_fullstack.c b/test/core/end2end/fixtures/chttp2_fullstack.c
index 53a6f0d7a57..0170dcf0e5a 100644
--- a/test/core/end2end/fixtures/chttp2_fullstack.c
+++ b/test/core/end2end/fixtures/chttp2_fullstack.c
@@ -64,7 +64,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
   gpr_join_host_port(&ffd->localaddr, "localhost", port);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -72,7 +72,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
 void chttp2_init_client_fullstack(grpc_end2end_test_fixture *f,
                                   grpc_channel_args *client_args) {
   fullstack_fixture_data *ffd = f->fixture_data;
-  f->client = grpc_insecure_channel_create(ffd->localaddr, client_args);
+  f->client = grpc_insecure_channel_create(ffd->localaddr, client_args, NULL);
   GPR_ASSERT(f->client);
 }
 
@@ -82,8 +82,8 @@ void chttp2_init_server_fullstack(grpc_end2end_test_fixture *f,
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_insecure_http2_port(f->server, ffd->localaddr));
   grpc_server_start(f->server);
 }
diff --git a/test/core/end2end/fixtures/chttp2_fullstack_compression.c b/test/core/end2end/fixtures/chttp2_fullstack_compression.c
index a75075d1d4f..6e7a1faf55a 100644
--- a/test/core/end2end/fixtures/chttp2_fullstack_compression.c
+++ b/test/core/end2end/fixtures/chttp2_fullstack_compression.c
@@ -69,7 +69,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack_compression(
 
   memset(&f, 0, sizeof(f));
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -83,7 +83,7 @@ void chttp2_init_client_fullstack_compression(grpc_end2end_test_fixture *f,
   ffd->client_args_compression = grpc_channel_args_set_compression_algorithm(
       client_args, GRPC_COMPRESS_GZIP);
   f->client = grpc_insecure_channel_create(ffd->localaddr,
-                                           ffd->client_args_compression);
+                                           ffd->client_args_compression, NULL);
 }
 
 void chttp2_init_server_fullstack_compression(grpc_end2end_test_fixture *f,
@@ -97,8 +97,8 @@ void chttp2_init_server_fullstack_compression(grpc_end2end_test_fixture *f,
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(ffd->server_args_compression);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(ffd->server_args_compression, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_insecure_http2_port(f->server, ffd->localaddr));
   grpc_server_start(f->server);
 }
diff --git a/test/core/end2end/fixtures/chttp2_fullstack_uds_posix.c b/test/core/end2end/fixtures/chttp2_fullstack_uds_posix.c
index 20afdb868e9..59d39bbb0fd 100644
--- a/test/core/end2end/fixtures/chttp2_fullstack_uds_posix.c
+++ b/test/core/end2end/fixtures/chttp2_fullstack_uds_posix.c
@@ -70,7 +70,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
                unique++);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -78,7 +78,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
 void chttp2_init_client_fullstack(grpc_end2end_test_fixture *f,
                                   grpc_channel_args *client_args) {
   fullstack_fixture_data *ffd = f->fixture_data;
-  f->client = grpc_insecure_channel_create(ffd->localaddr, client_args);
+  f->client = grpc_insecure_channel_create(ffd->localaddr, client_args, NULL);
 }
 
 void chttp2_init_server_fullstack(grpc_end2end_test_fixture *f,
@@ -87,8 +87,8 @@ void chttp2_init_server_fullstack(grpc_end2end_test_fixture *f,
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_insecure_http2_port(f->server, ffd->localaddr));
   grpc_server_start(f->server);
 }
diff --git a/test/core/end2end/fixtures/chttp2_fullstack_uds_posix_with_poll.c b/test/core/end2end/fixtures/chttp2_fullstack_uds_posix_with_poll.c
index 8491ea6970d..05b9ea09493 100644
--- a/test/core/end2end/fixtures/chttp2_fullstack_uds_posix_with_poll.c
+++ b/test/core/end2end/fixtures/chttp2_fullstack_uds_posix_with_poll.c
@@ -70,7 +70,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
                unique++);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -78,7 +78,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
 void chttp2_init_client_fullstack(grpc_end2end_test_fixture *f,
                                   grpc_channel_args *client_args) {
   fullstack_fixture_data *ffd = f->fixture_data;
-  f->client = grpc_insecure_channel_create(ffd->localaddr, client_args);
+  f->client = grpc_insecure_channel_create(ffd->localaddr, client_args, NULL);
 }
 
 void chttp2_init_server_fullstack(grpc_end2end_test_fixture *f,
@@ -87,8 +87,8 @@ void chttp2_init_server_fullstack(grpc_end2end_test_fixture *f,
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_insecure_http2_port(f->server, ffd->localaddr));
   grpc_server_start(f->server);
 }
diff --git a/test/core/end2end/fixtures/chttp2_fullstack_with_poll.c b/test/core/end2end/fixtures/chttp2_fullstack_with_poll.c
index 2a4835add12..48feefc9312 100644
--- a/test/core/end2end/fixtures/chttp2_fullstack_with_poll.c
+++ b/test/core/end2end/fixtures/chttp2_fullstack_with_poll.c
@@ -64,7 +64,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
   gpr_join_host_port(&ffd->localaddr, "localhost", port);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -72,7 +72,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
 void chttp2_init_client_fullstack(grpc_end2end_test_fixture *f,
                                   grpc_channel_args *client_args) {
   fullstack_fixture_data *ffd = f->fixture_data;
-  f->client = grpc_insecure_channel_create(ffd->localaddr, client_args);
+  f->client = grpc_insecure_channel_create(ffd->localaddr, client_args, NULL);
 }
 
 void chttp2_init_server_fullstack(grpc_end2end_test_fixture *f,
@@ -81,8 +81,8 @@ void chttp2_init_server_fullstack(grpc_end2end_test_fixture *f,
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_insecure_http2_port(f->server, ffd->localaddr));
   grpc_server_start(f->server);
 }
diff --git a/test/core/end2end/fixtures/chttp2_fullstack_with_proxy.c b/test/core/end2end/fixtures/chttp2_fullstack_with_proxy.c
index 248cc7d6e7f..44083e26762 100644
--- a/test/core/end2end/fixtures/chttp2_fullstack_with_proxy.c
+++ b/test/core/end2end/fixtures/chttp2_fullstack_with_proxy.c
@@ -56,13 +56,13 @@ typedef struct fullstack_fixture_data {
 } fullstack_fixture_data;
 
 static grpc_server *create_proxy_server(const char *port) {
-  grpc_server *s = grpc_server_create(NULL);
+  grpc_server *s = grpc_server_create(NULL, NULL);
   GPR_ASSERT(grpc_server_add_insecure_http2_port(s, port));
   return s;
 }
 
 static grpc_channel *create_proxy_client(const char *target) {
-  return grpc_insecure_channel_create(target, NULL);
+  return grpc_insecure_channel_create(target, NULL, NULL);
 }
 
 static const grpc_end2end_proxy_def proxy_def = {create_proxy_server,
@@ -77,7 +77,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
   ffd->proxy = grpc_end2end_proxy_create(&proxy_def);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -86,7 +86,7 @@ void chttp2_init_client_fullstack(grpc_end2end_test_fixture *f,
                                   grpc_channel_args *client_args) {
   fullstack_fixture_data *ffd = f->fixture_data;
   f->client = grpc_insecure_channel_create(
-      grpc_end2end_proxy_get_client_target(ffd->proxy), client_args);
+      grpc_end2end_proxy_get_client_target(ffd->proxy), client_args, NULL);
   GPR_ASSERT(f->client);
 }
 
@@ -96,8 +96,8 @@ void chttp2_init_server_fullstack(grpc_end2end_test_fixture *f,
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_insecure_http2_port(
       f->server, grpc_end2end_proxy_get_server_port(ffd->proxy)));
   grpc_server_start(f->server);
diff --git a/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack.c b/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack.c
index 9850aac69b0..491a293764c 100644
--- a/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack.c
+++ b/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack.c
@@ -63,7 +63,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_secure_fullstack(
   gpr_join_host_port(&ffd->localaddr, "localhost", port);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -92,8 +92,8 @@ static void chttp2_init_server_secure_fullstack(
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_secure_http2_port(f->server, ffd->localaddr,
                                                server_creds));
   grpc_server_credentials_release(server_creds);
diff --git a/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_poll.c b/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_poll.c
index 3df2acd296b..f2736cc92f9 100644
--- a/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_poll.c
+++ b/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_poll.c
@@ -63,7 +63,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_secure_fullstack(
   gpr_join_host_port(&ffd->localaddr, "localhost", port);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -92,8 +92,8 @@ static void chttp2_init_server_secure_fullstack(
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_secure_http2_port(f->server, ffd->localaddr,
                                                server_creds));
   grpc_server_credentials_release(server_creds);
diff --git a/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_proxy.c b/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_proxy.c
index 4d77039cac1..cc0b9dbbdd5 100644
--- a/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_proxy.c
+++ b/test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_proxy.c
@@ -54,7 +54,7 @@ typedef struct fullstack_secure_fixture_data {
 } fullstack_secure_fixture_data;
 
 static grpc_server *create_proxy_server(const char *port) {
-  grpc_server *s = grpc_server_create(NULL);
+  grpc_server *s = grpc_server_create(NULL, NULL);
   grpc_ssl_pem_key_cert_pair pem_cert_key_pair = {test_server1_key,
                                                   test_server1_cert};
   grpc_server_credentials *ssl_creds =
@@ -91,7 +91,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_secure_fullstack(
   ffd->proxy = grpc_end2end_proxy_create(&proxy_def);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -121,8 +121,8 @@ static void chttp2_init_server_secure_fullstack(
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_secure_http2_port(
       f->server, grpc_end2end_proxy_get_server_port(ffd->proxy), server_creds));
   grpc_server_credentials_release(server_creds);
diff --git a/test/core/end2end/fixtures/chttp2_simple_ssl_with_oauth2_fullstack.c b/test/core/end2end/fixtures/chttp2_simple_ssl_with_oauth2_fullstack.c
index 284d5f07ae9..3c35baec6bf 100644
--- a/test/core/end2end/fixtures/chttp2_simple_ssl_with_oauth2_fullstack.c
+++ b/test/core/end2end/fixtures/chttp2_simple_ssl_with_oauth2_fullstack.c
@@ -105,7 +105,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_secure_fullstack(
   gpr_join_host_port(&ffd->localaddr, "localhost", port);
 
   f.fixture_data = ffd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   return f;
 }
@@ -126,8 +126,8 @@ static void chttp2_init_server_secure_fullstack(
   if (f->server) {
     grpc_server_destroy(f->server);
   }
-  f->server = grpc_server_create(server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  f->server = grpc_server_create(server_args, NULL);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   GPR_ASSERT(grpc_server_add_secure_http2_port(f->server, ffd->localaddr,
                                                server_creds));
   grpc_server_credentials_release(server_creds);
diff --git a/test/core/end2end/fixtures/chttp2_socket_pair.c b/test/core/end2end/fixtures/chttp2_socket_pair.c
index 807fc8e7bc3..16a04fbebfa 100644
--- a/test/core/end2end/fixtures/chttp2_socket_pair.c
+++ b/test/core/end2end/fixtures/chttp2_socket_pair.c
@@ -95,7 +95,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_socketpair(
   grpc_end2end_test_fixture f;
   memset(&f, 0, sizeof(f));
   f.fixture_data = sfd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   *sfd = grpc_iomgr_create_endpoint_pair("fixture", 65536);
 
@@ -123,7 +123,7 @@ static void chttp2_init_server_socketpair(grpc_end2end_test_fixture *f,
   grpc_transport *transport;
   GPR_ASSERT(!f->server);
   f->server = grpc_server_create_from_filters(NULL, 0, server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   grpc_server_start(f->server);
   transport = grpc_create_chttp2_transport(server_args, sfd->server, mdctx, 0);
   server_setup_transport(f, transport, mdctx);
diff --git a/test/core/end2end/fixtures/chttp2_socket_pair_one_byte_at_a_time.c b/test/core/end2end/fixtures/chttp2_socket_pair_one_byte_at_a_time.c
index 21d4404237a..94fc36f5eca 100644
--- a/test/core/end2end/fixtures/chttp2_socket_pair_one_byte_at_a_time.c
+++ b/test/core/end2end/fixtures/chttp2_socket_pair_one_byte_at_a_time.c
@@ -95,7 +95,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_socketpair(
   grpc_end2end_test_fixture f;
   memset(&f, 0, sizeof(f));
   f.fixture_data = sfd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   *sfd = grpc_iomgr_create_endpoint_pair("fixture", 1);
 
@@ -123,7 +123,7 @@ static void chttp2_init_server_socketpair(grpc_end2end_test_fixture *f,
   grpc_transport *transport;
   GPR_ASSERT(!f->server);
   f->server = grpc_server_create_from_filters(NULL, 0, server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   grpc_server_start(f->server);
   transport = grpc_create_chttp2_transport(server_args, sfd->server, mdctx, 0);
   server_setup_transport(f, transport, mdctx);
diff --git a/test/core/end2end/fixtures/chttp2_socket_pair_with_grpc_trace.c b/test/core/end2end/fixtures/chttp2_socket_pair_with_grpc_trace.c
index 9d798ad1d20..588c4b23e1e 100644
--- a/test/core/end2end/fixtures/chttp2_socket_pair_with_grpc_trace.c
+++ b/test/core/end2end/fixtures/chttp2_socket_pair_with_grpc_trace.c
@@ -96,7 +96,7 @@ static grpc_end2end_test_fixture chttp2_create_fixture_socketpair(
   grpc_end2end_test_fixture f;
   memset(&f, 0, sizeof(f));
   f.fixture_data = sfd;
-  f.cq = grpc_completion_queue_create();
+  f.cq = grpc_completion_queue_create(NULL);
 
   *sfd = grpc_iomgr_create_endpoint_pair("fixture", 65536);
 
@@ -124,7 +124,7 @@ static void chttp2_init_server_socketpair(grpc_end2end_test_fixture *f,
   grpc_transport *transport;
   GPR_ASSERT(!f->server);
   f->server = grpc_server_create_from_filters(NULL, 0, server_args);
-  grpc_server_register_completion_queue(f->server, f->cq);
+  grpc_server_register_completion_queue(f->server, f->cq, NULL);
   grpc_server_start(f->server);
   transport = grpc_create_chttp2_transport(server_args, sfd->server, mdctx, 0);
   server_setup_transport(f, transport, mdctx);
diff --git a/test/core/end2end/fixtures/proxy.c b/test/core/end2end/fixtures/proxy.c
index e4f6263334c..798d4e94d45 100644
--- a/test/core/end2end/fixtures/proxy.c
+++ b/test/core/end2end/fixtures/proxy.c
@@ -100,11 +100,11 @@ grpc_end2end_proxy *grpc_end2end_proxy_create(
 
   gpr_join_host_port(&proxy->proxy_port, "localhost", proxy_port);
   gpr_join_host_port(&proxy->server_port, "localhost", server_port);
-  proxy->cq = grpc_completion_queue_create();
+  proxy->cq = grpc_completion_queue_create(NULL);
   proxy->server = def->create_server(proxy->proxy_port);
   proxy->client = def->create_client(proxy->server_port);
 
-  grpc_server_register_completion_queue(proxy->server, proxy->cq);
+  grpc_server_register_completion_queue(proxy->server, proxy->cq, NULL);
   grpc_server_start(proxy->server);
 
   gpr_thd_options_set_joinable(&opt);
@@ -178,7 +178,8 @@ static void on_p2s_recv_initial_metadata(void *arg, int success) {
     op.data.send_initial_metadata.metadata = pc->p2s_initial_metadata.metadata;
     refpc(pc, "on_c2p_sent_initial_metadata");
     err = grpc_call_start_batch(pc->c2p, &op, 1,
-                                new_closure(on_c2p_sent_initial_metadata, pc));
+                                new_closure(on_c2p_sent_initial_metadata, pc),
+                                NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
   }
 
@@ -204,7 +205,7 @@ static void on_p2s_sent_message(void *arg, int success) {
     op.data.recv_message = &pc->c2p_msg;
     refpc(pc, "on_c2p_recv_msg");
     err = grpc_call_start_batch(pc->c2p, &op, 1,
-                                new_closure(on_c2p_recv_msg, pc));
+                                new_closure(on_c2p_recv_msg, pc), NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
   }
 
@@ -228,14 +229,14 @@ static void on_c2p_recv_msg(void *arg, int success) {
       op.data.send_message = pc->c2p_msg;
       refpc(pc, "on_p2s_sent_message");
       err = grpc_call_start_batch(pc->p2s, &op, 1,
-                                  new_closure(on_p2s_sent_message, pc));
+                                  new_closure(on_p2s_sent_message, pc), NULL);
       GPR_ASSERT(err == GRPC_CALL_OK);
     } else {
       op.op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
       op.flags = 0;
       refpc(pc, "on_p2s_sent_close");
       err = grpc_call_start_batch(pc->p2s, &op, 1,
-                                  new_closure(on_p2s_sent_close, pc));
+                                  new_closure(on_p2s_sent_close, pc), NULL);
       GPR_ASSERT(err == GRPC_CALL_OK);
     }
   }
@@ -257,7 +258,7 @@ static void on_c2p_sent_message(void *arg, int success) {
     op.data.recv_message = &pc->p2s_msg;
     refpc(pc, "on_p2s_recv_msg");
     err = grpc_call_start_batch(pc->p2s, &op, 1,
-                                new_closure(on_p2s_recv_msg, pc));
+                                new_closure(on_p2s_recv_msg, pc), NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
   }
 
@@ -275,7 +276,7 @@ static void on_p2s_recv_msg(void *arg, int success) {
     op.data.send_message = pc->p2s_msg;
     refpc(pc, "on_c2p_sent_message");
     err = grpc_call_start_batch(pc->c2p, &op, 1,
-                                new_closure(on_c2p_sent_message, pc));
+                                new_closure(on_c2p_sent_message, pc), NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
   }
   unrefpc(pc, "on_p2s_recv_msg");
@@ -303,7 +304,7 @@ static void on_p2s_status(void *arg, int success) {
     op.data.send_status_from_server.status_details = pc->p2s_status_details;
     refpc(pc, "on_c2p_sent_status");
     err = grpc_call_start_batch(pc->c2p, &op, 1,
-                                new_closure(on_c2p_sent_status, pc));
+                                new_closure(on_c2p_sent_status, pc), NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
   }
 
@@ -330,7 +331,7 @@ static void on_new_call(void *arg, int success) {
     pc->p2s = grpc_channel_create_call(
         proxy->client, pc->c2p, GRPC_PROPAGATE_DEFAULTS, proxy->cq,
         proxy->new_call_details.method, proxy->new_call_details.host,
-        proxy->new_call_details.deadline);
+        proxy->new_call_details.deadline, NULL);
     gpr_ref_init(&pc->refs, 1);
 
     op.flags = 0;
@@ -339,7 +340,8 @@ static void on_new_call(void *arg, int success) {
     op.data.recv_initial_metadata = &pc->p2s_initial_metadata;
     refpc(pc, "on_p2s_recv_initial_metadata");
     err = grpc_call_start_batch(pc->p2s, &op, 1,
-                                new_closure(on_p2s_recv_initial_metadata, pc));
+                                new_closure(on_p2s_recv_initial_metadata, pc),
+                                NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
 
     op.op = GRPC_OP_SEND_INITIAL_METADATA;
@@ -347,21 +349,22 @@ static void on_new_call(void *arg, int success) {
     op.data.send_initial_metadata.metadata = pc->c2p_initial_metadata.metadata;
     refpc(pc, "on_p2s_sent_initial_metadata");
     err = grpc_call_start_batch(pc->p2s, &op, 1,
-                                new_closure(on_p2s_sent_initial_metadata, pc));
+                                new_closure(on_p2s_sent_initial_metadata, pc),
+                                NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
 
     op.op = GRPC_OP_RECV_MESSAGE;
     op.data.recv_message = &pc->c2p_msg;
     refpc(pc, "on_c2p_recv_msg");
     err = grpc_call_start_batch(pc->c2p, &op, 1,
-                                new_closure(on_c2p_recv_msg, pc));
+                                new_closure(on_c2p_recv_msg, pc), NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
 
     op.op = GRPC_OP_RECV_MESSAGE;
     op.data.recv_message = &pc->p2s_msg;
     refpc(pc, "on_p2s_recv_msg");
     err = grpc_call_start_batch(pc->p2s, &op, 1,
-                                new_closure(on_p2s_recv_msg, pc));
+                                new_closure(on_p2s_recv_msg, pc), NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
 
     op.op = GRPC_OP_RECV_STATUS_ON_CLIENT;
@@ -372,15 +375,15 @@ static void on_new_call(void *arg, int success) {
     op.data.recv_status_on_client.status_details_capacity =
         &pc->p2s_status_details_capacity;
     refpc(pc, "on_p2s_status");
-    err =
-        grpc_call_start_batch(pc->p2s, &op, 1, new_closure(on_p2s_status, pc));
+    err = grpc_call_start_batch(pc->p2s, &op, 1,
+                                new_closure(on_p2s_status, pc), NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
 
     op.op = GRPC_OP_RECV_CLOSE_ON_SERVER;
     op.data.recv_close_on_server.cancelled = &pc->c2p_server_cancelled;
     refpc(pc, "on_c2p_closed");
-    err =
-        grpc_call_start_batch(pc->c2p, &op, 1, new_closure(on_c2p_closed, pc));
+    err = grpc_call_start_batch(pc->c2p, &op, 1,
+                                new_closure(on_c2p_closed, pc), NULL);
     GPR_ASSERT(err == GRPC_CALL_OK);
 
     request_call(proxy);
@@ -405,7 +408,7 @@ static void thread_main(void *arg) {
   closure *cl;
   for (;;) {
     grpc_event ev = grpc_completion_queue_next(
-        proxy->cq, gpr_inf_future(GPR_CLOCK_MONOTONIC));
+        proxy->cq, gpr_inf_future(GPR_CLOCK_MONOTONIC), NULL);
     switch (ev.type) {
       case GRPC_QUEUE_TIMEOUT:
         gpr_log(GPR_ERROR, "Should never reach here");
diff --git a/test/core/end2end/multiple_server_queues_test.c b/test/core/end2end/multiple_server_queues_test.c
index 7772d14ba5f..2befcd0124f 100644
--- a/test/core/end2end/multiple_server_queues_test.c
+++ b/test/core/end2end/multiple_server_queues_test.c
@@ -41,20 +41,20 @@ int main(int argc, char **argv) {
 
   grpc_test_init(argc, argv);
   grpc_init();
-  cq1 = grpc_completion_queue_create();
-  cq2 = grpc_completion_queue_create();
-  server = grpc_server_create(NULL);
-  grpc_server_register_completion_queue(server, cq1);
+  cq1 = grpc_completion_queue_create(NULL);
+  cq2 = grpc_completion_queue_create(NULL);
+  server = grpc_server_create(NULL, NULL);
+  grpc_server_register_completion_queue(server, cq1, NULL);
   grpc_server_add_insecure_http2_port(server, "[::]:0");
-  grpc_server_register_completion_queue(server, cq2);
+  grpc_server_register_completion_queue(server, cq2, NULL);
   grpc_server_start(server);
   grpc_server_shutdown_and_notify(server, cq2, NULL);
   grpc_completion_queue_next(
-      cq2, gpr_inf_future(GPR_CLOCK_REALTIME)); /* cue queue hang */
+      cq2, gpr_inf_future(GPR_CLOCK_REALTIME), NULL); /* cue queue hang */
   grpc_completion_queue_shutdown(cq1);
   grpc_completion_queue_shutdown(cq2);
-  grpc_completion_queue_next(cq1, gpr_inf_future(GPR_CLOCK_REALTIME));
-  grpc_completion_queue_next(cq2, gpr_inf_future(GPR_CLOCK_REALTIME));
+  grpc_completion_queue_next(cq1, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
+  grpc_completion_queue_next(cq2, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   grpc_server_destroy(server);
   grpc_completion_queue_destroy(cq1);
   grpc_completion_queue_destroy(cq2);
diff --git a/test/core/end2end/no_server_test.c b/test/core/end2end/no_server_test.c
index 6a5e12325dd..6ae87288f7f 100644
--- a/test/core/end2end/no_server_test.c
+++ b/test/core/end2end/no_server_test.c
@@ -57,18 +57,19 @@ int main(int argc, char **argv) {
 
   grpc_metadata_array_init(&trailing_metadata_recv);
 
-  cq = grpc_completion_queue_create();
+  cq = grpc_completion_queue_create(NULL);
   cqv = cq_verifier_create(cq);
 
   /* create a call, channel to a non existant server */
-  chan = grpc_insecure_channel_create("nonexistant:54321", NULL);
+  chan = grpc_insecure_channel_create("nonexistant:54321", NULL, NULL);
   call = grpc_channel_create_call(chan, NULL, GRPC_PROPAGATE_DEFAULTS, cq,
-                                  "/Foo", "nonexistant", deadline);
+                                  "/Foo", "nonexistant", deadline, NULL);
 
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -76,9 +77,10 @@ int main(int argc, char **argv) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call, ops, op - ops, tag(1)));
+             grpc_call_start_batch(call, ops, op - ops, tag(1), NULL));
   /* verify that all tags get completed */
   cq_expect_completion(cqv, tag(1), 1);
   cq_verify(cqv);
@@ -86,8 +88,8 @@ int main(int argc, char **argv) {
   GPR_ASSERT(status == GRPC_STATUS_DEADLINE_EXCEEDED);
 
   grpc_completion_queue_shutdown(cq);
-  while (grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME))
-             .type != GRPC_QUEUE_SHUTDOWN)
+  while (grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME),
+                                    NULL).type != GRPC_QUEUE_SHUTDOWN)
     ;
   grpc_completion_queue_destroy(cq);
   grpc_call_destroy(call);
diff --git a/test/core/end2end/tests/bad_hostname.c b/test/core/end2end/tests/bad_hostname.c
index 501db89b7b2..61bbbe48558 100644
--- a/test/core/end2end/tests/bad_hostname.c
+++ b/test/core/end2end/tests/bad_hostname.c
@@ -70,7 +70,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -78,7 +78,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -110,11 +111,12 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "slartibartfast.local", deadline);
+                               "/foo", "slartibartfast.local", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -126,13 +128,16 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -140,8 +145,10 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(1), 1);
   cq_verify(cqv);
diff --git a/test/core/end2end/tests/cancel_after_accept.c b/test/core/end2end/tests/cancel_after_accept.c
index 2e166b84120..37151663484 100644
--- a/test/core/end2end/tests/cancel_after_accept.c
+++ b/test/core/end2end/tests/cancel_after_accept.c
@@ -69,7 +69,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -77,7 +77,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -114,6 +115,7 @@ static void test_cancel_after_accept(grpc_end2end_test_config config,
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   grpc_byte_buffer *request_payload_recv = NULL;
@@ -127,7 +129,7 @@ static void test_cancel_after_accept(grpc_end2end_test_config config,
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -142,28 +144,34 @@ static void test_cancel_after_accept(grpc_end2end_test_config config,
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(2)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq, tag(2));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(2), 1);
   cq_verify(cqv);
 
@@ -171,22 +179,27 @@ static void test_cancel_after_accept(grpc_end2end_test_config config,
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(3)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(3), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c));
+  GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c, NULL));
 
   cq_expect_completion(cqv, tag(3), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c b/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
index 171c1874cc3..ffb267c236e 100644
--- a/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
+++ b/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
@@ -69,7 +69,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -77,7 +77,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -114,6 +115,7 @@ static void test_cancel_after_accept_and_writes_closed(
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   grpc_byte_buffer *request_payload_recv = NULL;
@@ -127,7 +129,7 @@ static void test_cancel_after_accept_and_writes_closed(
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -142,31 +144,38 @@ static void test_cancel_after_accept_and_writes_closed(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(2)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq, tag(2));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(2), 1);
   cq_verify(cqv);
 
@@ -174,22 +183,27 @@ static void test_cancel_after_accept_and_writes_closed(
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(3)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(3), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c));
+  GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c, NULL));
 
   cq_expect_completion(cqv, tag(3), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/cancel_after_invoke.c b/test/core/end2end/tests/cancel_after_invoke.c
index 186cd44a43a..7e984da591f 100644
--- a/test/core/end2end/tests/cancel_after_invoke.c
+++ b/test/core/end2end/tests/cancel_after_invoke.c
@@ -70,7 +70,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -78,7 +78,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -114,6 +115,7 @@ static void test_cancel_after_invoke(grpc_end2end_test_config config,
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   grpc_byte_buffer *response_payload_recv = NULL;
@@ -122,7 +124,7 @@ static void test_cancel_after_invoke(grpc_end2end_test_config config,
       grpc_raw_byte_buffer_create(&request_payload_slice, 1);
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -137,29 +139,36 @@ static void test_cancel_after_invoke(grpc_end2end_test_config config,
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, test_ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, test_ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c));
+  GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c, NULL));
 
   cq_expect_completion(cqv, tag(1), 1);
   cq_verify(cqv);
diff --git a/test/core/end2end/tests/cancel_before_invoke.c b/test/core/end2end/tests/cancel_before_invoke.c
index b511908b4f9..06e66026816 100644
--- a/test/core/end2end/tests/cancel_before_invoke.c
+++ b/test/core/end2end/tests/cancel_before_invoke.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -112,6 +113,7 @@ static void test_cancel_before_invoke(grpc_end2end_test_config config,
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   grpc_byte_buffer *response_payload_recv = NULL;
@@ -120,10 +122,10 @@ static void test_cancel_before_invoke(grpc_end2end_test_config config,
       grpc_raw_byte_buffer_create(&request_payload_slice, 1);
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_cancel(c));
+  GPR_ASSERT(GRPC_CALL_OK == grpc_call_cancel(c, NULL));
 
   grpc_metadata_array_init(&initial_metadata_recv);
   grpc_metadata_array_init(&trailing_metadata_recv);
@@ -137,27 +139,34 @@ static void test_cancel_before_invoke(grpc_end2end_test_config config,
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, test_ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, test_ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(1), 1);
   cq_verify(cqv);
diff --git a/test/core/end2end/tests/cancel_in_a_vacuum.c b/test/core/end2end/tests/cancel_in_a_vacuum.c
index 7645410184f..f57a44caa4c 100644
--- a/test/core/end2end/tests/cancel_in_a_vacuum.c
+++ b/test/core/end2end/tests/cancel_in_a_vacuum.c
@@ -69,7 +69,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -77,7 +77,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -108,10 +109,10 @@ static void test_cancel_in_a_vacuum(grpc_end2end_test_config config,
   cq_verifier *v_client = cq_verifier_create(f.cq);
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
-  GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c));
+  GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c, NULL));
 
   grpc_call_destroy(c);
 
diff --git a/test/core/end2end/tests/cancel_test_helpers.h b/test/core/end2end/tests/cancel_test_helpers.h
index 8345c07904d..6ea822fa9ab 100644
--- a/test/core/end2end/tests/cancel_test_helpers.h
+++ b/test/core/end2end/tests/cancel_test_helpers.h
@@ -36,12 +36,13 @@
 
 typedef struct {
   const char *name;
-  grpc_call_error (*initiate_cancel)(grpc_call *call);
+  grpc_call_error (*initiate_cancel)(grpc_call *call, void *reserved);
   grpc_status_code expect_status;
   const char *expect_details;
 } cancellation_mode;
 
-static grpc_call_error wait_for_deadline(grpc_call *call) {
+static grpc_call_error wait_for_deadline(grpc_call *call, void *reserved) {
+  (void) reserved;
   return GRPC_CALL_OK;
 }
 
diff --git a/test/core/end2end/tests/census_simple_request.c b/test/core/end2end/tests/census_simple_request.c
index 2142dde9216..8f615dec20d 100644
--- a/test/core/end2end/tests/census_simple_request.c
+++ b/test/core/end2end/tests/census_simple_request.c
@@ -67,7 +67,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -82,7 +83,7 @@ static void shutdown_client(grpc_end2end_test_fixture *f) {
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, n_seconds_time(5));
+    ev = grpc_completion_queue_next(cq, n_seconds_time(5), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -107,12 +108,14 @@ static void test_body(grpc_end2end_test_fixture f) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr:1234", deadline);
+                               "/foo", "foo.test.google.fr:1234", deadline,
+                               NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -124,13 +127,16 @@ static void test_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -138,12 +144,15 @@ static void test_body(grpc_end2end_test_fixture f) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -151,18 +160,22 @@ static void test_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/default_host.c b/test/core/end2end/tests/default_host.c
index 920449f4fa3..5cbf26b94ff 100644
--- a/test/core/end2end/tests/default_host.c
+++ b/test/core/end2end/tests/default_host.c
@@ -70,7 +70,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -78,7 +78,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -111,13 +112,14 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
   char *peer;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", NULL, deadline);
+                               "/foo", NULL, deadline, NULL);
   GPR_ASSERT(c);
 
   peer = grpc_call_get_peer(c);
@@ -149,11 +151,13 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(error == GRPC_CALL_OK);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(error == GRPC_CALL_OK);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -181,7 +185,8 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(error == GRPC_CALL_OK);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/disappearing_server.c b/test/core/end2end/tests/disappearing_server.c
index 94bed336e81..0b98424c259 100644
--- a/test/core/end2end/tests/disappearing_server.c
+++ b/test/core/end2end/tests/disappearing_server.c
@@ -56,7 +56,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -93,12 +93,14 @@ static void do_request_and_shutdown_server(grpc_end2end_test_fixture *f,
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f->client, NULL, GRPC_PROPAGATE_DEFAULTS, f->cq,
-                               "/foo", "foo.test.google.fr:1234", deadline);
+                               "/foo", "foo.test.google.fr:1234", deadline,
+                               NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -110,13 +112,16 @@ static void do_request_and_shutdown_server(grpc_end2end_test_fixture *f,
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -124,13 +129,15 @@ static void do_request_and_shutdown_server(grpc_end2end_test_fixture *f,
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(f->server, &s,
-                                                      &call_details,
-                                                      &request_metadata_recv,
-                                                      f->cq, f->cq, tag(101)));
+  error = grpc_server_request_call(f->server, &s, &call_details,
+                                   &request_metadata_recv, f->cq, f->cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -142,18 +149,22 @@ static void do_request_and_shutdown_server(grpc_end2end_test_fixture *f,
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c b/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
index 36cbe8067bb..a5683129c1e 100644
--- a/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
+++ b/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -101,12 +101,13 @@ static void test_early_server_shutdown_finishes_inflight_calls(
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -119,13 +120,16 @@ static void test_early_server_shutdown_finishes_inflight_calls(
   op->data.send_initial_metadata.count = 0;
   op->data.send_initial_metadata.metadata = NULL;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -133,12 +137,15 @@ static void test_early_server_shutdown_finishes_inflight_calls(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -146,8 +153,10 @@ static void test_early_server_shutdown_finishes_inflight_calls(
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   /* shutdown and destroy the server */
   grpc_server_shutdown_and_notify(f.server, f.cq, tag(1000));
diff --git a/test/core/end2end/tests/early_server_shutdown_finishes_tags.c b/test/core/end2end/tests/early_server_shutdown_finishes_tags.c
index fc03cb01a81..9b678a17541 100644
--- a/test/core/end2end/tests/early_server_shutdown_finishes_tags.c
+++ b/test/core/end2end/tests/early_server_shutdown_finishes_tags.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
diff --git a/test/core/end2end/tests/empty_batch.c b/test/core/end2end/tests/empty_batch.c
index 138c6b07c58..feb2f18166f 100644
--- a/test/core/end2end/tests/empty_batch.c
+++ b/test/core/end2end/tests/empty_batch.c
@@ -70,7 +70,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -78,7 +78,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -103,13 +104,15 @@ static void empty_batch_body(grpc_end2end_test_fixture f) {
   grpc_call *c;
   gpr_timespec deadline = five_seconds_time();
   cq_verifier *cqv = cq_verifier_create(f.cq);
+  grpc_call_error error;
   grpc_op *op = NULL;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, op, 0, tag(1)));
+  error = grpc_call_start_batch(c, op, 0, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(1), 1);
   cq_verify(cqv);
 
diff --git a/test/core/end2end/tests/graceful_server_shutdown.c b/test/core/end2end/tests/graceful_server_shutdown.c
index 23efa0304ff..9ec9430d475 100644
--- a/test/core/end2end/tests/graceful_server_shutdown.c
+++ b/test/core/end2end/tests/graceful_server_shutdown.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -108,12 +108,13 @@ static void test_early_server_shutdown_finishes_inflight_calls(
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -126,13 +127,16 @@ static void test_early_server_shutdown_finishes_inflight_calls(
   op->data.send_initial_metadata.count = 0;
   op->data.send_initial_metadata.metadata = NULL;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -140,12 +144,15 @@ static void test_early_server_shutdown_finishes_inflight_calls(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -157,18 +164,22 @@ static void test_early_server_shutdown_finishes_inflight_calls(
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(0xdead), 1);
diff --git a/test/core/end2end/tests/invoke_large_request.c b/test/core/end2end/tests/invoke_large_request.c
index e32645e2bab..5fe369ea459 100644
--- a/test/core/end2end/tests/invoke_large_request.c
+++ b/test/core/end2end/tests/invoke_large_request.c
@@ -66,7 +66,7 @@ static gpr_timespec n_seconds_time(int n) {
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, n_seconds_time(5));
+    ev = grpc_completion_queue_next(cq, n_seconds_time(5), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -74,7 +74,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -124,12 +125,13 @@ static void test_invoke_large_request(grpc_end2end_test_config config) {
   grpc_byte_buffer *response_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -141,21 +143,26 @@ static void test_invoke_large_request(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -163,12 +170,15 @@ static void test_invoke_large_request(grpc_end2end_test_config config) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -176,12 +186,15 @@ static void test_invoke_large_request(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -190,18 +203,22 @@ static void test_invoke_large_request(grpc_end2end_test_config config) {
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/max_concurrent_streams.c b/test/core/end2end/tests/max_concurrent_streams.c
index 049c0288359..203d98d1004 100644
--- a/test/core/end2end/tests/max_concurrent_streams.c
+++ b/test/core/end2end/tests/max_concurrent_streams.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -109,12 +110,14 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr:1234", deadline);
+                               "/foo", "foo.test.google.fr:1234", deadline,
+                               NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -126,13 +129,16 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -140,12 +146,15 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -153,18 +162,22 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
@@ -207,6 +220,7 @@ static void test_max_concurrent_streams(grpc_end2end_test_config config) {
   grpc_metadata_array initial_metadata_recv2;
   grpc_metadata_array trailing_metadata_recv2;
   grpc_status_code status1;
+  grpc_call_error error;
   char *details1 = NULL;
   size_t details_capacity1 = 0;
   grpc_status_code status2;
@@ -245,10 +259,12 @@ static void test_max_concurrent_streams(grpc_end2end_test_config config) {
      the first completes */
   deadline = n_seconds_time(1000);
   c1 = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                                "/alpha", "foo.test.google.fr:1234", deadline);
+                                "/alpha", "foo.test.google.fr:1234", deadline,
+                                NULL);
   GPR_ASSERT(c1);
   c2 = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                                "/beta", "foo.test.google.fr:1234", deadline);
+                                "/beta", "foo.test.google.fr:1234", deadline,
+                                NULL);
   GPR_ASSERT(c2);
 
   GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
@@ -259,12 +275,14 @@ static void test_max_concurrent_streams(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(c1, ops, op - ops, tag(301)));
+  error = grpc_call_start_batch(c1, ops, op - ops, tag(301), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   op = ops;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
@@ -273,24 +291,28 @@ static void test_max_concurrent_streams(grpc_end2end_test_config config) {
   op->data.recv_status_on_client.status_details = &details1;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity1;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv1;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(c1, ops, op - ops, tag(302)));
+  error = grpc_call_start_batch(c1, ops, op - ops, tag(302), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(c2, ops, op - ops, tag(401)));
+  error = grpc_call_start_batch(c2, ops, op - ops, tag(401), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   op = ops;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
@@ -299,19 +321,22 @@ static void test_max_concurrent_streams(grpc_end2end_test_config config) {
   op->data.recv_status_on_client.status_details = &details2;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity2;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv1;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(c2, ops, op - ops, tag(402)));
+  error = grpc_call_start_batch(c2, ops, op - ops, tag(402), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   got_client_start = 0;
   got_server_start = 0;
   live_call = -1;
   while (!got_client_start || !got_server_start) {
-    ev = grpc_completion_queue_next(f.cq, GRPC_TIMEOUT_SECONDS_TO_DEADLINE(3));
+    ev = grpc_completion_queue_next(f.cq, GRPC_TIMEOUT_SECONDS_TO_DEADLINE(3),
+                                    NULL);
     GPR_ASSERT(ev.type == GRPC_OP_COMPLETE);
     GPR_ASSERT(ev.success);
     if (ev.tag == tag(101)) {
@@ -334,19 +359,22 @@ static void test_max_concurrent_streams(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(s1, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s1, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(live_call + 2), 1);
@@ -365,19 +393,22 @@ static void test_max_concurrent_streams(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(s2, ops, op - ops, tag(202)));
+  error = grpc_call_start_batch(s2, ops, op - ops, tag(202), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(live_call + 2), 1);
   cq_expect_completion(cqv, tag(202), 1);
diff --git a/test/core/end2end/tests/max_message_length.c b/test/core/end2end/tests/max_message_length.c
index feea49c68f1..dd30e68f42f 100644
--- a/test/core/end2end/tests/max_message_length.c
+++ b/test/core/end2end/tests/max_message_length.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -114,6 +115,7 @@ static void test_max_message_length(grpc_end2end_test_config config) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
@@ -130,7 +132,7 @@ static void test_max_message_length(grpc_end2end_test_config config) {
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
                                "/foo", "foo.test.google.fr:1234",
-                               gpr_inf_future(GPR_CLOCK_REALTIME));
+                               gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -142,17 +144,21 @@ static void test_max_message_length(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -160,12 +166,15 @@ static void test_max_message_length(grpc_end2end_test_config config) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -173,8 +182,10 @@ static void test_max_message_length(grpc_end2end_test_config config) {
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/no_op.c b/test/core/end2end/tests/no_op.c
index 8ead6647580..565d4ea2806 100644
--- a/test/core/end2end/tests/no_op.c
+++ b/test/core/end2end/tests/no_op.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
diff --git a/test/core/end2end/tests/ping_pong_streaming.c b/test/core/end2end/tests/ping_pong_streaming.c
index 0ae611b5184..e19f115e404 100644
--- a/test/core/end2end/tests/ping_pong_streaming.c
+++ b/test/core/end2end/tests/ping_pong_streaming.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -113,6 +114,7 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
@@ -125,7 +127,8 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
   gpr_slice response_payload_slice = gpr_slice_from_copied_string("hello you");
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr:1234", deadline);
+                               "/foo", "foo.test.google.fr:1234", deadline,
+                               NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -137,10 +140,12 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -148,12 +153,15 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(100)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(100));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(100), 1);
   cq_verify(cqv);
 
@@ -161,12 +169,15 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(101)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(101), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   for (i = 0; i < messages; i++) {
     request_payload = grpc_raw_byte_buffer_create(&request_payload_slice, 1);
@@ -176,20 +187,24 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
     op->op = GRPC_OP_SEND_MESSAGE;
     op->data.send_message = request_payload;
     op->flags = 0;
+    op->reserved = NULL;
     op++;
     op->op = GRPC_OP_RECV_MESSAGE;
     op->data.recv_message = &response_payload_recv;
     op->flags = 0;
+    op->reserved = NULL;
     op++;
-    GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(2)));
+    error = grpc_call_start_batch(c, ops, op - ops, tag(2), NULL);
+    GPR_ASSERT(GRPC_CALL_OK == error);
 
     op = ops;
     op->op = GRPC_OP_RECV_MESSAGE;
     op->data.recv_message = &request_payload_recv;
     op->flags = 0;
+    op->reserved = NULL;
     op++;
-    GPR_ASSERT(GRPC_CALL_OK ==
-               grpc_call_start_batch(s, ops, op - ops, tag(102)));
+    error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+    GPR_ASSERT(GRPC_CALL_OK == error);
     cq_expect_completion(cqv, tag(102), 1);
     cq_verify(cqv);
 
@@ -197,9 +212,10 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
     op->op = GRPC_OP_SEND_MESSAGE;
     op->data.send_message = response_payload;
     op->flags = 0;
+    op->reserved = NULL;
     op++;
-    GPR_ASSERT(GRPC_CALL_OK ==
-               grpc_call_start_batch(s, ops, op - ops, tag(103)));
+    error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+    GPR_ASSERT(GRPC_CALL_OK == error);
     cq_expect_completion(cqv, tag(103), 1);
     cq_expect_completion(cqv, tag(2), 1);
     cq_verify(cqv);
@@ -216,8 +232,10 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
   op = ops;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(3)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(3), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   op = ops;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
@@ -225,8 +243,10 @@ static void test_pingpong_streaming(grpc_end2end_test_config config,
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(104)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(104), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(1), 1);
   cq_expect_completion(cqv, tag(3), 1);
diff --git a/test/core/end2end/tests/registered_call.c b/test/core/end2end/tests/registered_call.c
index ffc4cd40a01..1ef595ee567 100644
--- a/test/core/end2end/tests/registered_call.c
+++ b/test/core/end2end/tests/registered_call.c
@@ -70,7 +70,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -78,7 +78,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -111,12 +112,13 @@ static void simple_request_body(grpc_end2end_test_fixture f, void *rc) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_registered_call(
-      f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq, rc, deadline);
+      f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq, rc, deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -128,13 +130,16 @@ static void simple_request_body(grpc_end2end_test_fixture f, void *rc) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -142,12 +147,15 @@ static void simple_request_body(grpc_end2end_test_fixture f, void *rc) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -155,18 +163,22 @@ static void simple_request_body(grpc_end2end_test_fixture f, void *rc) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
@@ -194,7 +206,8 @@ static void test_invoke_simple_request(grpc_end2end_test_config config) {
   grpc_end2end_test_fixture f =
       begin_test(config, "test_invoke_simple_request", NULL, NULL);
   void *rc =
-      grpc_channel_register_call(f.client, "/foo", "foo.test.google.fr:1234");
+      grpc_channel_register_call(f.client, "/foo", "foo.test.google.fr:1234",
+                                 NULL);
 
   simple_request_body(f, rc);
   end_test(&f);
@@ -206,7 +219,8 @@ static void test_invoke_10_simple_requests(grpc_end2end_test_config config) {
   grpc_end2end_test_fixture f =
       begin_test(config, "test_invoke_10_simple_requests", NULL, NULL);
   void *rc =
-      grpc_channel_register_call(f.client, "/foo", "foo.test.google.fr:1234");
+      grpc_channel_register_call(f.client, "/foo", "foo.test.google.fr:1234",
+                                 NULL);
 
   for (i = 0; i < 10; i++) {
     simple_request_body(f, rc);
diff --git a/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
index 600642e6a7e..de6f4607952 100644
--- a/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -113,20 +114,24 @@ static void test_request_response_with_metadata_and_payload(
       {"key1-bin",
        "\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc",
        13,
-       {{NULL, NULL, NULL}}},
+       0,
+       {{NULL, NULL, NULL, NULL}}},
       {"key2-bin",
        "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d",
        14,
-       {{NULL, NULL, NULL}}}};
+       0,
+       {{NULL, NULL, NULL, NULL}}}};
   grpc_metadata meta_s[2] = {
       {"key3-bin",
        "\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee",
        15,
-       {{NULL, NULL, NULL}}},
+       0,
+       {{NULL, NULL, NULL, NULL}}},
       {"key4-bin",
        "\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff",
        16,
-       {{NULL, NULL, NULL}}}};
+       0,
+       {{NULL, NULL, NULL, NULL}}}};
   grpc_end2end_test_fixture f = begin_test(
       config, "test_request_response_with_metadata_and_payload", NULL, NULL);
   cq_verifier *cqv = cq_verifier_create(f.cq);
@@ -139,12 +144,13 @@ static void test_request_response_with_metadata_and_payload(
   grpc_byte_buffer *response_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -157,21 +163,26 @@ static void test_request_response_with_metadata_and_payload(
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -179,12 +190,15 @@ static void test_request_response_with_metadata_and_payload(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -193,12 +207,15 @@ static void test_request_response_with_metadata_and_payload(
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -207,18 +224,22 @@ static void test_request_response_with_metadata_and_payload(
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/request_response_with_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_metadata_and_payload.c
index 7e8cce10f40..b6196ab46e6 100644
--- a/test/core/end2end/tests/request_response_with_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_metadata_and_payload.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -109,10 +110,10 @@ static void test_request_response_with_metadata_and_payload(
   grpc_byte_buffer *response_payload =
       grpc_raw_byte_buffer_create(&response_payload_slice, 1);
   gpr_timespec deadline = five_seconds_time();
-  grpc_metadata meta_c[2] = {{"key1", "val1", 4, {{NULL, NULL, NULL}}},
-                             {"key2", "val2", 4, {{NULL, NULL, NULL}}}};
-  grpc_metadata meta_s[2] = {{"KeY3", "val3", 4, {{NULL, NULL, NULL}}},
-                             {"KeY4", "val4", 4, {{NULL, NULL, NULL}}}};
+  grpc_metadata meta_c[2] = {{"key1", "val1", 4, 0, {{NULL, NULL, NULL, NULL}}},
+                             {"key2", "val2", 4, 0, {{NULL, NULL, NULL, NULL}}}};
+  grpc_metadata meta_s[2] = {{"KeY3", "val3", 4, 0, {{NULL, NULL, NULL, NULL}}},
+                             {"KeY4", "val4", 4, 0, {{NULL, NULL, NULL, NULL}}}};
   grpc_end2end_test_fixture f = begin_test(
       config, "test_request_response_with_metadata_and_payload", NULL, NULL);
   cq_verifier *cqv = cq_verifier_create(f.cq);
@@ -125,12 +126,13 @@ static void test_request_response_with_metadata_and_payload(
   grpc_byte_buffer *response_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -143,21 +145,26 @@ static void test_request_response_with_metadata_and_payload(
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -165,12 +172,15 @@ static void test_request_response_with_metadata_and_payload(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -179,12 +189,15 @@ static void test_request_response_with_metadata_and_payload(
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -193,18 +206,22 @@ static void test_request_response_with_metadata_and_payload(
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/request_response_with_payload.c b/test/core/end2end/tests/request_response_with_payload.c
index 55323895fb7..0a45a482a33 100644
--- a/test/core/end2end/tests/request_response_with_payload.c
+++ b/test/core/end2end/tests/request_response_with_payload.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -117,12 +118,13 @@ static void request_response_with_payload(grpc_end2end_test_fixture f) {
   grpc_byte_buffer *response_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -134,21 +136,26 @@ static void request_response_with_payload(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -156,12 +163,15 @@ static void request_response_with_payload(grpc_end2end_test_fixture f) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -169,12 +179,15 @@ static void request_response_with_payload(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -183,18 +196,22 @@ static void request_response_with_payload(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/request_response_with_payload_and_call_creds.c b/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
index 342dfa03f6b..8e0bc4e2ae1 100644
--- a/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
+++ b/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
@@ -86,7 +86,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -94,7 +94,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -139,7 +140,7 @@ static void test_call_creds_failure(grpc_end2end_test_config config) {
       begin_test(config, "test_call_creds_failure", 0);
   gpr_timespec deadline = five_seconds_time();
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   /* Try with credentials unfit to be set on a call (channel creds). */
@@ -176,6 +177,7 @@ static void request_response_with_payload_and_call_creds(
   grpc_byte_buffer *response_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
@@ -187,7 +189,7 @@ static void request_response_with_payload_and_call_creds(
   cqv = cq_verifier_create(f.cq);
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
   creds = grpc_iam_credentials_create(iam_token, iam_selector);
   GPR_ASSERT(creds != NULL);
@@ -217,21 +219,26 @@ static void request_response_with_payload_and_call_creds(
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -239,12 +246,15 @@ static void request_response_with_payload_and_call_creds(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
   s_auth_context = grpc_call_auth_context(s);
@@ -264,12 +274,15 @@ static void request_response_with_payload_and_call_creds(
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -278,18 +291,22 @@ static void request_response_with_payload_and_call_creds(
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
@@ -389,6 +406,7 @@ static void test_request_with_server_rejecting_client_creds(
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   grpc_byte_buffer *response_payload_recv = NULL;
@@ -401,7 +419,7 @@ static void test_request_with_server_rejecting_client_creds(
   cqv = cq_verifier_create(f.cq);
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   creds = grpc_iam_credentials_create(iam_token, iam_selector);
@@ -441,7 +459,8 @@ static void test_request_with_server_rejecting_client_creds(
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(error == GRPC_CALL_OK);
 
   cq_expect_completion(cqv, tag(1), 1);
   cq_verify(cqv);
diff --git a/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
index 26be4ef643c..83744a8e242 100644
--- a/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -109,12 +110,12 @@ static void test_request_response_with_metadata_and_payload(
   grpc_byte_buffer *response_payload =
       grpc_raw_byte_buffer_create(&response_payload_slice, 1);
   gpr_timespec deadline = five_seconds_time();
-  grpc_metadata meta_c[2] = {{"key1", "val1", 4, {{NULL, NULL, NULL}}},
-                             {"key2", "val2", 4, {{NULL, NULL, NULL}}}};
-  grpc_metadata meta_s[2] = {{"key3", "val3", 4, {{NULL, NULL, NULL}}},
-                             {"key4", "val4", 4, {{NULL, NULL, NULL}}}};
-  grpc_metadata meta_t[2] = {{"key5", "val5", 4, {{NULL, NULL, NULL}}},
-                             {"key6", "val6", 4, {{NULL, NULL, NULL}}}};
+  grpc_metadata meta_c[2] = {{"key1", "val1", 4, 0, {{NULL, NULL, NULL, NULL}}},
+                             {"key2", "val2", 4, 0, {{NULL, NULL, NULL, NULL}}}};
+  grpc_metadata meta_s[2] = {{"key3", "val3", 4, 0, {{NULL, NULL, NULL, NULL}}},
+                             {"key4", "val4", 4, 0, {{NULL, NULL, NULL, NULL}}}};
+  grpc_metadata meta_t[2] = {{"key5", "val5", 4, 0, {{NULL, NULL, NULL, NULL}}},
+                             {"key6", "val6", 4, 0, {{NULL, NULL, NULL, NULL}}}};
   grpc_end2end_test_fixture f = begin_test(
       config, "test_request_response_with_metadata_and_payload", NULL, NULL);
   cq_verifier *cqv = cq_verifier_create(f.cq);
@@ -127,12 +128,13 @@ static void test_request_response_with_metadata_and_payload(
   grpc_byte_buffer *response_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -145,21 +147,26 @@ static void test_request_response_with_metadata_and_payload(
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -167,12 +174,15 @@ static void test_request_response_with_metadata_and_payload(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -181,12 +191,15 @@ static void test_request_response_with_metadata_and_payload(
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -195,10 +208,12 @@ static void test_request_response_with_metadata_and_payload(
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 2;
@@ -206,8 +221,10 @@ static void test_request_response_with_metadata_and_payload(
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/request_with_compressed_payload.c b/test/core/end2end/tests/request_with_compressed_payload.c
index 5f7d83cb068..e749988518d 100644
--- a/test/core/end2end/tests/request_with_compressed_payload.c
+++ b/test/core/end2end/tests/request_with_compressed_payload.c
@@ -72,7 +72,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -80,7 +80,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -123,6 +124,7 @@ static void request_with_payload_template(
   grpc_byte_buffer *request_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
@@ -142,7 +144,7 @@ static void request_with_payload_template(
   cqv = cq_verifier_create(f.cq);
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -159,17 +161,21 @@ static void request_with_payload_template(
     op->data.send_initial_metadata.count = 0;
   }
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = send_flags_bitmask;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -177,13 +183,15 @@ static void request_with_payload_template(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_server_request_call(f.server, &s, &call_details,
-                                      &request_metadata_recv, f.cq,
-                                      f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq,
+                                   f.cq, tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -191,12 +199,15 @@ static void request_with_payload_template(
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -205,14 +216,17 @@ static void request_with_payload_template(
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/request_with_flags.c b/test/core/end2end/tests/request_with_flags.c
index 37c4825c8b2..3255f144574 100644
--- a/test/core/end2end/tests/request_with_flags.c
+++ b/test/core/end2end/tests/request_with_flags.c
@@ -69,7 +69,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -77,7 +77,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -117,12 +118,13 @@ static void test_invoke_request_with_flags(
   grpc_byte_buffer *request_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   grpc_call_error expectation;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -134,17 +136,21 @@ static void test_invoke_request_with_flags(
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -152,9 +158,11 @@ static void test_invoke_request_with_flags(
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   expectation = call_start_batch_expected_result;
-  GPR_ASSERT(expectation == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(expectation == error);
 
   if (expectation == GRPC_CALL_OK) {
     cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/request_with_large_metadata.c b/test/core/end2end/tests/request_with_large_metadata.c
index 9ea8273ab0e..5b43caf18c0 100644
--- a/test/core/end2end/tests/request_with_large_metadata.c
+++ b/test/core/end2end/tests/request_with_large_metadata.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -117,13 +118,14 @@ static void test_request_with_large_metadata(grpc_end2end_test_config config) {
   grpc_byte_buffer *request_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
   const int large_size = 64 * 1024;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   meta.key = "key";
@@ -142,17 +144,21 @@ static void test_request_with_large_metadata(grpc_end2end_test_config config) {
   op->data.send_initial_metadata.count = 1;
   op->data.send_initial_metadata.metadata = &meta;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -160,12 +166,15 @@ static void test_request_with_large_metadata(grpc_end2end_test_config config) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -173,12 +182,15 @@ static void test_request_with_large_metadata(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -187,14 +199,17 @@ static void test_request_with_large_metadata(grpc_end2end_test_config config) {
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/request_with_payload.c b/test/core/end2end/tests/request_with_payload.c
index 6b5f173f011..c0013fb60fc 100644
--- a/test/core/end2end/tests/request_with_payload.c
+++ b/test/core/end2end/tests/request_with_payload.c
@@ -68,7 +68,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -76,7 +76,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -116,12 +117,13 @@ static void test_invoke_request_with_payload(grpc_end2end_test_config config) {
   grpc_byte_buffer *request_payload_recv = NULL;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -133,17 +135,21 @@ static void test_invoke_request_with_payload(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -151,8 +157,10 @@ static void test_invoke_request_with_payload(grpc_end2end_test_config config) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
                                  f.server, &s, &call_details,
@@ -164,12 +172,15 @@ static void test_invoke_request_with_payload(grpc_end2end_test_config config) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_verify(cqv);
@@ -178,14 +189,17 @@ static void test_invoke_request_with_payload(grpc_end2end_test_config config) {
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(103), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/server_finishes_request.c b/test/core/end2end/tests/server_finishes_request.c
index 661c099d937..ab2f5752636 100644
--- a/test/core/end2end/tests/server_finishes_request.c
+++ b/test/core/end2end/tests/server_finishes_request.c
@@ -70,7 +70,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -78,7 +78,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -111,12 +112,14 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr:1234", deadline);
+                               "/foo", "foo.test.google.fr:1234", deadline,
+                               NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -128,10 +131,12 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -139,12 +144,15 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -152,18 +160,22 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/simple_delayed_request.c b/test/core/end2end/tests/simple_delayed_request.c
index 82d2bf96570..277aa2596e5 100644
--- a/test/core/end2end/tests/simple_delayed_request.c
+++ b/test/core/end2end/tests/simple_delayed_request.c
@@ -56,7 +56,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -64,7 +64,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -101,6 +102,7 @@ static void simple_delayed_request_body(grpc_end2end_test_config config,
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
@@ -108,7 +110,7 @@ static void simple_delayed_request_body(grpc_end2end_test_config config,
   config.init_client(f, client_args);
 
   c = grpc_channel_create_call(f->client, NULL, GRPC_PROPAGATE_DEFAULTS, f->cq,
-                               "/foo", "foo.test.google.fr", deadline);
+                               "/foo", "foo.test.google.fr", deadline, NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -120,13 +122,16 @@ static void simple_delayed_request_body(grpc_end2end_test_config config,
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -134,15 +139,17 @@ static void simple_delayed_request_body(grpc_end2end_test_config config,
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   config.init_server(f, server_args);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(f->server, &s,
-                                                      &call_details,
-                                                      &request_metadata_recv,
-                                                      f->cq, f->cq, tag(101)));
+  error = grpc_server_request_call(f->server, &s, &call_details,
+                                   &request_metadata_recv, f->cq, f->cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -150,18 +157,22 @@ static void simple_delayed_request_body(grpc_end2end_test_config config,
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/simple_request.c b/test/core/end2end/tests/simple_request.c
index d60a63e682a..d3d2f275604 100644
--- a/test/core/end2end/tests/simple_request.c
+++ b/test/core/end2end/tests/simple_request.c
@@ -70,7 +70,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -78,7 +78,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -111,13 +112,15 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
   char *peer;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr:1234", deadline);
+                               "/foo", "foo.test.google.fr:1234", deadline,
+                               NULL);
   GPR_ASSERT(c);
 
   peer = grpc_call_get_peer(c);
@@ -134,13 +137,16 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -148,12 +154,15 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -170,18 +179,22 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c b/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
index 2244e22416c..4fc206cbfcb 100644
--- a/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
+++ b/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
@@ -70,7 +70,7 @@ static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 static void drain_cq(grpc_completion_queue *cq) {
   grpc_event ev;
   do {
-    ev = grpc_completion_queue_next(cq, five_seconds_time());
+    ev = grpc_completion_queue_next(cq, five_seconds_time(), NULL);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -78,7 +78,8 @@ static void shutdown_server(grpc_end2end_test_fixture *f) {
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->cq, tag(1000),
-                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                                         GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5),
+                                         NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;
@@ -111,12 +112,14 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   grpc_metadata_array request_metadata_recv;
   grpc_call_details call_details;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
   int was_cancelled = 2;
 
   c = grpc_channel_create_call(f.client, NULL, GRPC_PROPAGATE_DEFAULTS, f.cq,
-                               "/foo", "foo.test.google.fr:1234", deadline);
+                               "/foo", "foo.test.google.fr:1234", deadline,
+                               NULL);
   GPR_ASSERT(c);
 
   grpc_metadata_array_init(&initial_metadata_recv);
@@ -128,13 +131,16 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -142,12 +148,15 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
-                                 f.server, &s, &call_details,
-                                 &request_metadata_recv, f.cq, f.cq, tag(101)));
+  error = grpc_server_request_call(f.server, &s, &call_details,
+                                   &request_metadata_recv, f.cq, f.cq,
+                                   tag(101));
+  GPR_ASSERT(GRPC_CALL_OK == error);
   cq_expect_completion(cqv, tag(101), 1);
   cq_verify(cqv);
 
@@ -155,18 +164,22 @@ static void simple_request_body(grpc_end2end_test_fixture f) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
+  error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   cq_expect_completion(cqv, tag(102), 1);
   cq_expect_completion(cqv, tag(1), 1);
diff --git a/test/core/fling/client.c b/test/core/fling/client.c
index 17b737c9dd4..54c92745107 100644
--- a/test/core/fling/client.c
+++ b/test/core/fling/client.c
@@ -91,24 +91,25 @@ static void init_ping_pong_request(void) {
 static void step_ping_pong_request(void) {
   call = grpc_channel_create_call(channel, NULL, GRPC_PROPAGATE_DEFAULTS, cq,
                                   "/Reflector/reflectUnary", "localhost",
-                                  gpr_inf_future(GPR_CLOCK_REALTIME));
+                                  gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call, ops, op - ops, (void *)1));
-  grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME));
+             grpc_call_start_batch(call, ops, op - ops, (void *)1, NULL));
+  grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   grpc_call_destroy(call);
   grpc_byte_buffer_destroy(response_payload_recv);
   call = NULL;
 }
 
 static void init_ping_pong_stream(void) {
+  grpc_call_error error;
   call = grpc_channel_create_call(channel, NULL, GRPC_PROPAGATE_DEFAULTS, cq,
                                   "/Reflector/reflectStream", "localhost",
-                                  gpr_inf_future(GPR_CLOCK_REALTIME));
+                                  gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   stream_init_op.op = GRPC_OP_SEND_INITIAL_METADATA;
   stream_init_op.data.send_initial_metadata.count = 0;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call, &stream_init_op, 1, (void *)1));
-  grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME));
+  error = grpc_call_start_batch(call, &stream_init_op, 1, (void *)1, NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
+  grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
 
   grpc_metadata_array_init(&initial_metadata_recv);
 
@@ -119,9 +120,10 @@ static void init_ping_pong_stream(void) {
 }
 
 static void step_ping_pong_stream(void) {
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call, stream_step_ops, 2, (void *)1));
-  grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME));
+  grpc_call_error error;
+  error = grpc_call_start_batch(call, stream_step_ops, 2, (void *)1, NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
+  grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
   grpc_byte_buffer_destroy(response_payload_recv);
 }
 
@@ -152,6 +154,7 @@ int main(int argc, char **argv) {
   int secure = 0;
   char *target = "localhost:443";
   gpr_cmdline *cl;
+  grpc_event event;
   char *scenario_name = "ping-pong-request";
   scenario sc = {NULL, NULL, NULL};
 
@@ -183,8 +186,8 @@ int main(int argc, char **argv) {
     return 1;
   }
 
-  channel = grpc_insecure_channel_create(target, NULL);
-  cq = grpc_completion_queue_create();
+  channel = grpc_insecure_channel_create(target, NULL, NULL);
+  cq = grpc_completion_queue_create(NULL);
   the_buffer = grpc_raw_byte_buffer_create(&slice, payload_size);
   histogram = gpr_histogram_create(0.01, 60e9);
 
@@ -210,9 +213,10 @@ int main(int argc, char **argv) {
 
   grpc_channel_destroy(channel);
   grpc_completion_queue_shutdown(cq);
-  while (grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME))
-             .type != GRPC_QUEUE_SHUTDOWN)
-    ;
+  do {
+    event = grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME),
+                                       NULL);
+  } while (event.type != GRPC_QUEUE_SHUTDOWN);
   grpc_completion_queue_destroy(cq);
   grpc_byte_buffer_destroy(the_buffer);
   gpr_slice_unref(slice);
diff --git a/test/core/fling/server.c b/test/core/fling/server.c
index f445c681782..2873e4af4b6 100644
--- a/test/core/fling/server.c
+++ b/test/core/fling/server.c
@@ -97,6 +97,7 @@ static void request_call(void) {
 
 static void handle_unary_method(void) {
   grpc_op *op;
+  grpc_call_error error;
 
   grpc_metadata_array_init(&initial_metadata_send);
 
@@ -122,41 +123,47 @@ static void handle_unary_method(void) {
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op++;
 
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call, unary_ops, op - unary_ops,
-                                   tag(FLING_SERVER_BATCH_OPS_FOR_UNARY)));
+  error = grpc_call_start_batch(call, unary_ops, op - unary_ops,
+                                tag(FLING_SERVER_BATCH_OPS_FOR_UNARY), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 }
 
 static void send_initial_metadata(void) {
+  grpc_call_error error;
+  void *tagarg = tag(FLING_SERVER_SEND_INIT_METADATA_FOR_STREAMING);
   grpc_metadata_array_init(&initial_metadata_send);
   metadata_send_op.op = GRPC_OP_SEND_INITIAL_METADATA;
   metadata_send_op.data.send_initial_metadata.count = 0;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(
-                 call, &metadata_send_op, 1,
-                 tag(FLING_SERVER_SEND_INIT_METADATA_FOR_STREAMING)));
+  error = grpc_call_start_batch(call, &metadata_send_op, 1, tagarg, NULL);
+
+  GPR_ASSERT(GRPC_CALL_OK == error);
 }
 
 static void start_read_op(int t) {
+  grpc_call_error error;
   /* Starting read at server */
   read_op.op = GRPC_OP_RECV_MESSAGE;
   read_op.data.recv_message = &payload_buffer;
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call, &read_op, 1, tag(t)));
+  error = grpc_call_start_batch(call, &read_op, 1, tag(t), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 }
 
 static void start_write_op(void) {
+  grpc_call_error error;
+  void *tagarg = tag(FLING_SERVER_WRITE_FOR_STREAMING);
   /* Starting write at server */
   write_op.op = GRPC_OP_SEND_MESSAGE;
   if (payload_buffer == NULL) {
     gpr_log(GPR_INFO, "NULL payload buffer !!!");
   }
   write_op.data.send_message = payload_buffer;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call, &write_op, 1,
-                                   tag(FLING_SERVER_WRITE_FOR_STREAMING)));
+  error = grpc_call_start_batch(call, &write_op, 1, tagarg, NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 }
 
 static void start_send_status(void) {
+  grpc_call_error error;
+  void *tagarg = tag(FLING_SERVER_SEND_STATUS_FOR_STREAMING);
   status_op[0].op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   status_op[0].data.send_status_from_server.status = GRPC_STATUS_OK;
   status_op[0].data.send_status_from_server.trailing_metadata_count = 0;
@@ -164,9 +171,8 @@ static void start_send_status(void) {
   status_op[1].op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   status_op[1].data.recv_close_on_server.cancelled = &was_cancelled;
 
-  GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(
-                                 call, status_op, 2,
-                                 tag(FLING_SERVER_SEND_STATUS_FOR_STREAMING)));
+  error = grpc_call_start_batch(call, status_op, 2, tagarg, NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 }
 
 /* We have some sort of deadlock, so let's not exit gracefully for now.
@@ -205,20 +211,20 @@ int main(int argc, char **argv) {
   }
   gpr_log(GPR_INFO, "creating server on: %s", addr);
 
-  cq = grpc_completion_queue_create();
+  cq = grpc_completion_queue_create(NULL);
   if (secure) {
     grpc_ssl_pem_key_cert_pair pem_key_cert_pair = {test_server1_key,
                                                     test_server1_cert};
     grpc_server_credentials *ssl_creds =
         grpc_ssl_server_credentials_create(NULL, &pem_key_cert_pair, 1, 0);
-    server = grpc_server_create(NULL);
+    server = grpc_server_create(NULL, NULL);
     GPR_ASSERT(grpc_server_add_secure_http2_port(server, addr, ssl_creds));
     grpc_server_credentials_release(ssl_creds);
   } else {
-    server = grpc_server_create(NULL);
+    server = grpc_server_create(NULL, NULL);
     GPR_ASSERT(grpc_server_add_insecure_http2_port(server, addr));
   }
-  grpc_server_register_completion_queue(server, cq);
+  grpc_server_register_completion_queue(server, cq, NULL);
   grpc_server_start(server);
 
   gpr_free(addr_buf);
@@ -235,14 +241,14 @@ int main(int argc, char **argv) {
       gpr_log(GPR_INFO, "Shutting down due to SIGINT");
       grpc_server_shutdown_and_notify(server, cq, tag(1000));
       GPR_ASSERT(grpc_completion_queue_pluck(
-                     cq, tag(1000), GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5))
+                     cq, tag(1000), GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5), NULL)
                      .type == GRPC_OP_COMPLETE);
       grpc_completion_queue_shutdown(cq);
       shutdown_started = 1;
     }
     ev = grpc_completion_queue_next(
         cq, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
-                         gpr_time_from_micros(1000000, GPR_TIMESPAN)));
+                         gpr_time_from_micros(1000000, GPR_TIMESPAN)), NULL);
     s = ev.tag;
     switch (ev.type) {
       case GRPC_OP_COMPLETE:
diff --git a/test/core/surface/completion_queue_test.c b/test/core/surface/completion_queue_test.c
index 0e59ea4b226..0741ab920df 100644
--- a/test/core/surface/completion_queue_test.c
+++ b/test/core/surface/completion_queue_test.c
@@ -52,7 +52,7 @@ static void *create_test_tag(void) {
 static void shutdown_and_destroy(grpc_completion_queue *cc) {
   grpc_event ev;
   grpc_completion_queue_shutdown(cc);
-  ev = grpc_completion_queue_next(cc, gpr_inf_past(GPR_CLOCK_REALTIME));
+  ev = grpc_completion_queue_next(cc, gpr_inf_past(GPR_CLOCK_REALTIME), NULL);
   GPR_ASSERT(ev.type == GRPC_QUEUE_SHUTDOWN);
   grpc_completion_queue_destroy(cc);
 }
@@ -60,17 +60,18 @@ static void shutdown_and_destroy(grpc_completion_queue *cc) {
 /* ensure we can create and destroy a completion channel */
 static void test_no_op(void) {
   LOG_TEST("test_no_op");
-  shutdown_and_destroy(grpc_completion_queue_create());
+  shutdown_and_destroy(grpc_completion_queue_create(NULL));
 }
 
 static void test_wait_empty(void) {
   grpc_completion_queue *cc;
+  grpc_event event;
 
   LOG_TEST("test_wait_empty");
 
-  cc = grpc_completion_queue_create();
-  GPR_ASSERT(grpc_completion_queue_next(cc, gpr_now(GPR_CLOCK_REALTIME)).type ==
-             GRPC_QUEUE_TIMEOUT);
+  cc = grpc_completion_queue_create(NULL);
+  event = grpc_completion_queue_next(cc, gpr_now(GPR_CLOCK_REALTIME), NULL);
+  GPR_ASSERT(event.type == GRPC_QUEUE_TIMEOUT);
   shutdown_and_destroy(cc);
 }
 
@@ -84,12 +85,12 @@ static void test_cq_end_op(void) {
 
   LOG_TEST("test_cq_end_op");
 
-  cc = grpc_completion_queue_create();
+  cc = grpc_completion_queue_create(NULL);
 
   grpc_cq_begin_op(cc);
   grpc_cq_end_op(cc, tag, 1, do_nothing_end_completion, NULL, &completion);
 
-  ev = grpc_completion_queue_next(cc, gpr_inf_past(GPR_CLOCK_REALTIME));
+  ev = grpc_completion_queue_next(cc, gpr_inf_past(GPR_CLOCK_REALTIME), NULL);
   GPR_ASSERT(ev.type == GRPC_OP_COMPLETE);
   GPR_ASSERT(ev.tag == tag);
   GPR_ASSERT(ev.success);
@@ -99,23 +100,27 @@ static void test_cq_end_op(void) {
 
 static void test_shutdown_then_next_polling(void) {
   grpc_completion_queue *cc;
+  grpc_event event;
   LOG_TEST("test_shutdown_then_next_polling");
 
-  cc = grpc_completion_queue_create();
+  cc = grpc_completion_queue_create(NULL);
   grpc_completion_queue_shutdown(cc);
-  GPR_ASSERT(grpc_completion_queue_next(cc, gpr_inf_past(GPR_CLOCK_REALTIME))
-                 .type == GRPC_QUEUE_SHUTDOWN);
+  event = grpc_completion_queue_next(cc, gpr_inf_past(GPR_CLOCK_REALTIME),
+                                     NULL);
+  GPR_ASSERT(event.type == GRPC_QUEUE_SHUTDOWN);
   grpc_completion_queue_destroy(cc);
 }
 
 static void test_shutdown_then_next_with_timeout(void) {
   grpc_completion_queue *cc;
+  grpc_event event;
   LOG_TEST("test_shutdown_then_next_with_timeout");
 
-  cc = grpc_completion_queue_create();
+  cc = grpc_completion_queue_create(NULL);
   grpc_completion_queue_shutdown(cc);
-  GPR_ASSERT(grpc_completion_queue_next(cc, gpr_inf_future(GPR_CLOCK_REALTIME))
-                 .type == GRPC_QUEUE_SHUTDOWN);
+  event = grpc_completion_queue_next(cc, gpr_inf_future(GPR_CLOCK_REALTIME),
+                                     NULL);
+  GPR_ASSERT(event.type == GRPC_QUEUE_SHUTDOWN);
   grpc_completion_queue_destroy(cc);
 }
 
@@ -135,7 +140,7 @@ static void test_pluck(void) {
     }
   }
 
-  cc = grpc_completion_queue_create();
+  cc = grpc_completion_queue_create(NULL);
 
   for (i = 0; i < GPR_ARRAY_SIZE(tags); i++) {
     grpc_cq_begin_op(cc);
@@ -145,7 +150,7 @@ static void test_pluck(void) {
 
   for (i = 0; i < GPR_ARRAY_SIZE(tags); i++) {
     ev = grpc_completion_queue_pluck(cc, tags[i],
-                                     gpr_inf_past(GPR_CLOCK_REALTIME));
+                                     gpr_inf_past(GPR_CLOCK_REALTIME), NULL);
     GPR_ASSERT(ev.tag == tags[i]);
   }
 
@@ -157,7 +162,7 @@ static void test_pluck(void) {
 
   for (i = 0; i < GPR_ARRAY_SIZE(tags); i++) {
     ev = grpc_completion_queue_pluck(cc, tags[GPR_ARRAY_SIZE(tags) - i - 1],
-                                     gpr_inf_past(GPR_CLOCK_REALTIME));
+                                     gpr_inf_past(GPR_CLOCK_REALTIME), NULL);
     GPR_ASSERT(ev.tag == tags[GPR_ARRAY_SIZE(tags) - i - 1]);
   }
 
@@ -229,7 +234,7 @@ static void consumer_thread(void *arg) {
 
   gpr_log(GPR_INFO, "consumer %d phase 2", opt->id);
   for (;;) {
-    ev = grpc_completion_queue_next(opt->cc, ten_seconds_time());
+    ev = grpc_completion_queue_next(opt->cc, ten_seconds_time(), NULL);
     switch (ev.type) {
       case GRPC_OP_COMPLETE:
         GPR_ASSERT(ev.success);
@@ -251,7 +256,7 @@ static void test_threading(int producers, int consumers) {
       gpr_malloc((producers + consumers) * sizeof(test_thread_options));
   gpr_event phase1 = GPR_EVENT_INIT;
   gpr_event phase2 = GPR_EVENT_INIT;
-  grpc_completion_queue *cc = grpc_completion_queue_create();
+  grpc_completion_queue *cc = grpc_completion_queue_create(NULL);
   int i;
   int total_consumed = 0;
   static int optid = 101;
diff --git a/test/core/surface/lame_client_test.c b/test/core/surface/lame_client_test.c
index 5e6c9ae15c6..216eeca8e1b 100644
--- a/test/core/surface/lame_client_test.c
+++ b/test/core/surface/lame_client_test.c
@@ -49,6 +49,7 @@ int main(int argc, char **argv) {
   grpc_op *op;
   grpc_metadata_array trailing_metadata_recv;
   grpc_status_code status;
+  grpc_call_error error;
   char *details = NULL;
   size_t details_capacity = 0;
 
@@ -59,10 +60,11 @@ int main(int argc, char **argv) {
 
   chan = grpc_lame_client_channel_create("lampoon:national");
   GPR_ASSERT(chan);
-  cq = grpc_completion_queue_create();
+  cq = grpc_completion_queue_create(NULL);
   call = grpc_channel_create_call(chan, NULL, GRPC_PROPAGATE_DEFAULTS, cq,
                                   "/Foo", "anywhere",
-                                  GRPC_TIMEOUT_SECONDS_TO_DEADLINE(100));
+                                  GRPC_TIMEOUT_SECONDS_TO_DEADLINE(100),
+                                  NULL);
   GPR_ASSERT(call);
   cqv = cq_verifier_create(cq);
 
@@ -70,6 +72,7 @@ int main(int argc, char **argv) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -77,9 +80,10 @@ int main(int argc, char **argv) {
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
-  GPR_ASSERT(GRPC_CALL_OK ==
-             grpc_call_start_batch(call, ops, op - ops, tag(1)));
+  error = grpc_call_start_batch(call, ops, op - ops, tag(1), NULL);
+  GPR_ASSERT(GRPC_CALL_OK == error);
 
   /* the call should immediately fail */
   cq_expect_completion(cqv, tag(1), 1);