diff --git a/doc/tutorials/introduction/cross_referencing/tutorial_cross_referencing.markdown b/doc/tutorials/introduction/cross_referencing/tutorial_cross_referencing.markdown
index daa7c396cd..ed13c3e030 100644
--- a/doc/tutorials/introduction/cross_referencing/tutorial_cross_referencing.markdown
+++ b/doc/tutorials/introduction/cross_referencing/tutorial_cross_referencing.markdown
@@ -39,14 +39,14 @@ Open your Doxyfile using your favorite text editor and search for the key
 `TAGFILES`. Change it as follows:
 
 @code
-TAGFILES = ./docs/doxygen-tags/opencv.tag=http://docs.opencv.org/3.4.19
+TAGFILES = ./docs/doxygen-tags/opencv.tag=http://docs.opencv.org/3.4.20
 @endcode
 
 If you had other definitions already, you can append the line using a `\`:
 
 @code
 TAGFILES = ./docs/doxygen-tags/libstdc++.tag=https://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen \
-           ./docs/doxygen-tags/opencv.tag=http://docs.opencv.org/3.4.19
+           ./docs/doxygen-tags/opencv.tag=http://docs.opencv.org/3.4.20
 @endcode
 
 Doxygen can now use the information from the tag file to link to the OpenCV
diff --git a/modules/core/include/opencv2/core/version.hpp b/modules/core/include/opencv2/core/version.hpp
index e355498735..e4418b7857 100644
--- a/modules/core/include/opencv2/core/version.hpp
+++ b/modules/core/include/opencv2/core/version.hpp
@@ -7,8 +7,8 @@
 
 #define CV_VERSION_MAJOR    3
 #define CV_VERSION_MINOR    4
-#define CV_VERSION_REVISION 19
-#define CV_VERSION_STATUS   "-dev"
+#define CV_VERSION_REVISION 20
+#define CV_VERSION_STATUS   "-pre"
 
 #define CVAUX_STR_EXP(__A)  #__A
 #define CVAUX_STR(__A)      CVAUX_STR_EXP(__A)
diff --git a/modules/python/package/setup.py b/modules/python/package/setup.py
index 1356931720..d91cb1d51a 100644
--- a/modules/python/package/setup.py
+++ b/modules/python/package/setup.py
@@ -9,7 +9,7 @@ def main():
     os.chdir(SCRIPT_DIR)
 
     package_name = 'opencv'
-    package_version = os.environ.get('OPENCV_VERSION', '3.4.19')  # TODO
+    package_version = os.environ.get('OPENCV_VERSION', '3.4.20')  # TODO
 
     long_description = 'Open Source Computer Vision Library Python bindings'  # TODO
 
diff --git a/platforms/android/build_sdk.py b/platforms/android/build_sdk.py
index 3a9618b835..62799a91a1 100755
--- a/platforms/android/build_sdk.py
+++ b/platforms/android/build_sdk.py
@@ -269,7 +269,7 @@ class Builder:
         # Add extra data
         apkxmldest = check_dir(os.path.join(apkdest, "res", "xml"), create=True)
         apklibdest = check_dir(os.path.join(apkdest, "libs", abi.name), create=True)
-        for ver, d in self.extra_packs + [("3.4.19", os.path.join(self.libdest, "lib"))]:
+        for ver, d in self.extra_packs + [("3.4.20", os.path.join(self.libdest, "lib"))]:
             r = ET.Element("library", attrib={"version": ver})
             log.info("Adding libraries from %s", d)
 
diff --git a/platforms/android/service/readme.txt b/platforms/android/service/readme.txt
index 11e9f0bae8..fec5c6746a 100644
--- a/platforms/android/service/readme.txt
+++ b/platforms/android/service/readme.txt
@@ -12,7 +12,7 @@ manually using adb tool:
 
     adb install <path-to-OpenCV-sdk>/apk/OpenCV_<version>_Manager_<app_version>_<platform>.apk
 
-Example: OpenCV_3.4.19-dev_Manager_3.49_armeabi-v7a.apk
+Example: OpenCV_3.4.20-dev_Manager_3.49_armeabi-v7a.apk
 
 Use the list of platforms below to determine proper OpenCV Manager package for your device:
 
diff --git a/platforms/maven/opencv-it/pom.xml b/platforms/maven/opencv-it/pom.xml
index befb75fed5..5955905b9b 100644
--- a/platforms/maven/opencv-it/pom.xml
+++ b/platforms/maven/opencv-it/pom.xml
@@ -4,7 +4,7 @@
     <parent>
         <groupId>org.opencv</groupId>
         <artifactId>opencv-parent</artifactId>
-        <version>3.4.19</version>
+        <version>3.4.20</version>
     </parent>
     <groupId>org.opencv</groupId>
     <artifactId>opencv-it</artifactId>
diff --git a/platforms/maven/opencv/pom.xml b/platforms/maven/opencv/pom.xml
index 0ff0c6fe2f..354d15d334 100644
--- a/platforms/maven/opencv/pom.xml
+++ b/platforms/maven/opencv/pom.xml
@@ -4,7 +4,7 @@
     <parent>
         <groupId>org.opencv</groupId>
         <artifactId>opencv-parent</artifactId>
-        <version>3.4.19</version>
+        <version>3.4.20</version>
     </parent>
     <groupId>org.opencv</groupId>
     <artifactId>opencv</artifactId>
diff --git a/platforms/maven/pom.xml b/platforms/maven/pom.xml
index 19ba7d07b3..04aa302c41 100644
--- a/platforms/maven/pom.xml
+++ b/platforms/maven/pom.xml
@@ -3,7 +3,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>org.opencv</groupId>
     <artifactId>opencv-parent</artifactId>
-    <version>3.4.19</version>
+    <version>3.4.20</version>
     <packaging>pom</packaging>
     <name>OpenCV Parent POM</name>
     <licenses>