diff --git a/CHANGES.txt b/CHANGES.txt
index 6da3dbd1cb2f..05677842fbd1 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,3 +1,24 @@
+2022-07-19 version 21.3 (C++/Java/Python/PHP/Objective-C/C#/Ruby)
+  C++
+  * Add header search paths to Protobuf-C++.podspec (#10024)
+  * Fixed Visual Studio constinit errors (#10232)
+  * Fix #9947: make the ABI compatible between debug and non-debug builds (#10271)
+
+  UPB
+  * Allow empty package names (fixes behavior regression in 4.21.0)
+  * Fix a SEGV bug when comparing a non-materialized sub-message (#10208)
+  * Fix several bugs in descriptor mapping containers (eg. descriptor.services_by_name)
+    * for x in mapping now yields keys rather than values, to match Python conventions and the behavior of the old library.
+    * Lookup operations now correctly reject unhashable types as map keys.
+    * We implement repr() to use the same format as dict.
+  * Fix maps to use the ScalarMapContainer class when appropriate
+
+  PHP
+  * Add "readonly" as a keyword for PHP and add previous classnames to descriptor pool (#10041)
+
+  Python
+  * Make //:protobuf_python and //:well_known_types_py_pb2 public (#10118)
+
 2022-06-27 version 21.2 (C++/Java/Python/PHP/Objective-C/C#/Ruby)
   C++
   * ArenaString improvements (fix alignment issue)
diff --git a/Protobuf-C++.podspec b/Protobuf-C++.podspec
index e34d3430dec2..c8a516bb0563 100644
--- a/Protobuf-C++.podspec
+++ b/Protobuf-C++.podspec
@@ -35,6 +35,7 @@ Pod::Spec.new do |s|
     # Do not let src/google/protobuf/stubs/time.h override system API
     'USE_HEADERMAP' => 'NO',
     'ALWAYS_SEARCH_USER_PATHS' => 'NO',
+    'HEADER_SEARCH_PATHS' => '"$(PODS_TARGET_SRCROOT)/src"'
   }
 
 end
diff --git a/protobuf_deps.bzl b/protobuf_deps.bzl
index 05d5fc25a6a6..66a19013e95c 100644
--- a/protobuf_deps.bzl
+++ b/protobuf_deps.bzl
@@ -114,6 +114,6 @@ def protobuf_deps():
         _github_archive(
             name = "upb",
             repo = "https://github.com/protocolbuffers/upb",
-            commit = "553fd5c2a77aefd4ef565e339efa8b828b8d078e",
-            sha256 = "6d7e139f2359104f960e045690cf1e326efd1ef3de51aa08362ecd27e1d25636"
+            commit = "dad71550bdf01fd057c9e284fb73c5ffc8098984",
+            sha256 = "47b0c810b5830cd7fe7388b4f540d6d25fe4e511beb3412e1f92e21079b48dec"
         )
diff --git a/src/google/protobuf/message_lite.cc b/src/google/protobuf/message_lite.cc
index 3a1b67bf66af..da66c1965b4c 100644
--- a/src/google/protobuf/message_lite.cc
+++ b/src/google/protobuf/message_lite.cc
@@ -520,18 +520,14 @@ void GenericTypeHandler<std::string>::Merge(const std::string& from,
   *to = from;
 }
 
-// Non-inline implementations of InternalMetadata routines
-#if defined(NDEBUG) || defined(_MSC_VER)
-// for opt and MSVC builds, the destructor is defined in the header.
-#else
+// Non-inline implementations of InternalMetadata destructor
 // This is moved out of the header because the GOOGLE_DCHECK produces a lot of code.
-InternalMetadata::~InternalMetadata() {
+void InternalMetadata::CheckedDestruct() {
   if (HasMessageOwnedArenaTag()) {
     GOOGLE_DCHECK(!HasUnknownFieldsTag());
     delete reinterpret_cast<Arena*>(ptr_ - kMessageOwnedArenaTagMask);
   }
 }
-#endif
 
 // Non-inline variants of std::string specializations for
 // various InternalMetadata routines.
diff --git a/src/google/protobuf/metadata_lite.h b/src/google/protobuf/metadata_lite.h
index 11faba69fca6..0c31517f08af 100644
--- a/src/google/protobuf/metadata_lite.h
+++ b/src/google/protobuf/metadata_lite.h
@@ -74,15 +74,19 @@ class PROTOBUF_EXPORT InternalMetadata {
     GOOGLE_DCHECK(!is_message_owned || arena != nullptr);
   }
 
-#if defined(NDEBUG) || defined(_MSC_VER)
+  // To keep the ABI identical between debug and non-debug builds,
+  // the destructor is always defined here even though it may delegate
+  // to a non-inline private method.
+  // (see https://github.com/protocolbuffers/protobuf/issues/9947)
   ~InternalMetadata() {
+#if defined(NDEBUG) || defined(_MSC_VER)
     if (HasMessageOwnedArenaTag()) {
       delete reinterpret_cast<Arena*>(ptr_ - kMessageOwnedArenaTagMask);
     }
-  }
 #else
-  ~InternalMetadata();
+    CheckedDestruct();
 #endif
+  }
 
   template <typename T>
   void Delete() {
@@ -261,6 +265,9 @@ class PROTOBUF_EXPORT InternalMetadata {
   PROTOBUF_NOINLINE void DoSwap(T* other) {
     mutable_unknown_fields<T>()->Swap(other);
   }
+
+  // Private helper with debug checks for ~InternalMetadata()
+  void CheckedDestruct();
 };
 
 // String Template specializations.
diff --git a/src/google/protobuf/port_def.inc b/src/google/protobuf/port_def.inc
index 8858e1936826..10005bf46526 100644
--- a/src/google/protobuf/port_def.inc
+++ b/src/google/protobuf/port_def.inc
@@ -638,14 +638,15 @@
 #ifdef PROTOBUF_CONSTINIT
 #error PROTOBUF_CONSTINIT was previously defined
 #endif
-#if defined(__cpp_constinit)
+#if defined(__cpp_constinit) && !defined(_MSC_VER)
 #define PROTOBUF_CONSTINIT constinit
 #define PROTOBUF_CONSTEXPR constexpr
 // Some older Clang versions incorrectly raise an error about
 // constant-initializing weak default instance pointers. Versions 12.0 and
 // higher seem to work, except that XCode 12.5.1 shows the error even though it
 // uses Clang 12.0.5.
-#elif __has_cpp_attribute(clang::require_constant_initialization) && \
+// Clang-cl on Windows raises error also.
+#elif !defined(_MSC_VER) && __has_cpp_attribute(clang::require_constant_initialization) && \
     ((defined(__APPLE__) && __clang_major__ >= 13) ||                \
      (!defined(__APPLE__) && __clang_major__ >= 12))
 #define PROTOBUF_CONSTINIT [[clang::require_constant_initialization]]
@@ -653,6 +654,10 @@
 #elif PROTOBUF_GNUC_MIN(12, 2)
 #define PROTOBUF_CONSTINIT __constinit
 #define PROTOBUF_CONSTEXPR constexpr
+// MSVC 17 currently seems to raise an error about constant-initialized pointers.
+#elif defined(_MSC_VER) && _MSC_VER >= 1930
+#define PROTOBUF_CONSTINIT
+#define PROTOBUF_CONSTEXPR constexpr
 #else
 #define PROTOBUF_CONSTINIT
 #define PROTOBUF_CONSTEXPR