diff --git a/conformance/binary_json_conformance_suite.cc b/conformance/binary_json_conformance_suite.cc
index 1399611748..15de2a578d 100644
--- a/conformance/binary_json_conformance_suite.cc
+++ b/conformance/binary_json_conformance_suite.cc
@@ -1367,7 +1367,7 @@ void BinaryAndJsonConformanceSuiteImpl<MessageType>::TestIllegalTags() {
 }
 
 template <typename MessageType>
-void BinaryAndJsonConformanceSuiteImpl<MessageType>::TestUnmatchedEndGroup() {
+void BinaryAndJsonConformanceSuiteImpl<MessageType>::TestUnmatchedGroup() {
   ExpectParseFailureForProto(tag(201, WireFormatLite::WIRETYPE_END_GROUP),
                              "UnmatchedEndGroup", REQUIRED);
   ExpectParseFailureForProto(tag(1234, WireFormatLite::WIRETYPE_END_GROUP),
@@ -1384,6 +1384,23 @@ void BinaryAndJsonConformanceSuiteImpl<MessageType>::TestUnmatchedEndGroup() {
       absl::StrCat(tag(1, WireFormatLite::WIRETYPE_END_GROUP),
                    len(2, "hello world")),
       "UnmatchedEndGroupWithData", REQUIRED);
+
+  ExpectParseFailureForProto(tag(201, WireFormatLite::WIRETYPE_START_GROUP),
+                             "UnmatchedStartGroup", REQUIRED);
+  ExpectParseFailureForProto(tag(1234, WireFormatLite::WIRETYPE_START_GROUP),
+                             "UnmatchedStartGroupUnknown", REQUIRED);
+  ExpectParseFailureForProto(tag(1, WireFormatLite::WIRETYPE_START_GROUP),
+                             "UnmatchedStartGroupWrongType", REQUIRED);
+  ExpectParseFailureForProto(
+      len(18, tag(1234, WireFormatLite::WIRETYPE_START_GROUP)),
+      "UnmatchedStartGroupNestedLen", REQUIRED);
+  ExpectParseFailureForProto(
+      group(201, tag(202, WireFormatLite::WIRETYPE_START_GROUP)),
+      "UnmatchedStartGroupNested", REQUIRED);
+  ExpectParseFailureForProto(
+      absl::StrCat(tag(1, WireFormatLite::WIRETYPE_START_GROUP),
+                   len(2, "hello world")),
+      "UnmatchedStartGroupWithData", REQUIRED);
 }
 
 template <typename MessageType>
@@ -1573,7 +1590,7 @@ void BinaryAndJsonConformanceSuiteImpl<MessageType>::RunAllTests() {
     }
 
     TestIllegalTags();
-    TestUnmatchedEndGroup();
+    TestUnmatchedGroup();
     TestUnknownWireType();
 
     int64_t kInt64Min = -9223372036854775808ULL;
diff --git a/conformance/binary_json_conformance_suite.h b/conformance/binary_json_conformance_suite.h
index 3166eb4897..9c990557d7 100644
--- a/conformance/binary_json_conformance_suite.h
+++ b/conformance/binary_json_conformance_suite.h
@@ -143,7 +143,7 @@ class BinaryAndJsonConformanceSuiteImpl {
                                       ConformanceLevel level);
   void TestPrematureEOFForType(google::protobuf::FieldDescriptor::Type type);
   void TestIllegalTags();
-  void TestUnmatchedEndGroup();
+  void TestUnmatchedGroup();
   void TestUnknownWireType();
   void TestOneofMessage();
   void TestUnknownMessage();
diff --git a/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs b/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs
deleted file mode 100644
index 208ce1fcb6..0000000000
--- a/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-#region Copyright notice and license
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-#endregion
-
-namespace Google.Protobuf.Reflection;
-
-internal sealed partial class FeatureSetDescriptor
-{
-    // Canonical serialized form of the edition defaults, generated by embed_edition_defaults.
-    private const string DefaultsBase64 =
-        "ChMYhAciACoMCAEQAhgCIAMoATACChMY5wciACoMCAIQARgBIAIoATABChMY6AciDAgBEAEYASACKAEwASoAIOYHKOgH";
-}