diff --git a/csharp/src/Google.Protobuf/Google.Protobuf.csproj b/csharp/src/Google.Protobuf/Google.Protobuf.csproj
index 5de33586db01..bed643fd49bd 100644
--- a/csharp/src/Google.Protobuf/Google.Protobuf.csproj
+++ b/csharp/src/Google.Protobuf/Google.Protobuf.csproj
@@ -9,12 +9,6 @@
     <LangVersion>10.0</LangVersion>
     <Authors>Google Inc.</Authors>
     <TargetFrameworks>netstandard1.1;netstandard2.0;net45;net50</TargetFrameworks>
-    <!-- 
-      - We're aware we target older frameworks, for compatibility.
-      - Framework choice is reviewed periodically (and definitely on
-      - major version changes).
-      -->
-    <CheckEolTargetFramework>false</CheckEolTargetFramework>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <AssemblyOriginatorKeyFile>../../keys/Google.Protobuf.snk</AssemblyOriginatorKeyFile>
     <SignAssembly>true</SignAssembly>
diff --git a/java/kotlin-lite/src/test/kotlin/com/google/protobuf/Proto2LiteTest.kt b/java/kotlin-lite/src/test/kotlin/com/google/protobuf/Proto2LiteTest.kt
index b858b1412575..93efe9cba7a9 100644
--- a/java/kotlin-lite/src/test/kotlin/com/google/protobuf/Proto2LiteTest.kt
+++ b/java/kotlin-lite/src/test/kotlin/com/google/protobuf/Proto2LiteTest.kt
@@ -404,38 +404,57 @@ class Proto2LiteTest {
   fun testExtensionsSet() {
     assertThat(
         testAllExtensionsLite {
-          this[UnittestLite.optionalInt32ExtensionLite] = 101
-          this[UnittestLite.optionalInt64ExtensionLite] = 102L
-          this[UnittestLite.optionalUint32ExtensionLite] = 103
-          this[UnittestLite.optionalUint64ExtensionLite] = 104L
-          this[UnittestLite.optionalSint32ExtensionLite] = 105
-          this[UnittestLite.optionalSint64ExtensionLite] = 106L
-          this[UnittestLite.optionalFixed32ExtensionLite] = 107
-          this[UnittestLite.optionalFixed64ExtensionLite] = 108L
-          this[UnittestLite.optionalSfixed32ExtensionLite] = 109
-          this[UnittestLite.optionalSfixed64ExtensionLite] = 110L
-          this[UnittestLite.optionalFloatExtensionLite] = 111F
-          this[UnittestLite.optionalDoubleExtensionLite] = 112.0
-          this[UnittestLite.optionalBoolExtensionLite] = true
-          this[UnittestLite.optionalStringExtensionLite] = "115"
-          this[UnittestLite.optionalBytesExtensionLite] = toBytes("116")
-          this[UnittestLite.optionalGroupExtensionLite] = optionalGroupExtensionLite { a = 117 }
-          this[UnittestLite.optionalNestedMessageExtensionLite] =
+          setExtension(UnittestLite.optionalInt32ExtensionLite, 101)
+          setExtension(UnittestLite.optionalInt64ExtensionLite, 102L)
+          setExtension(UnittestLite.optionalUint32ExtensionLite, 103)
+          setExtension(UnittestLite.optionalUint64ExtensionLite, 104L)
+          setExtension(UnittestLite.optionalSint32ExtensionLite, 105)
+          setExtension(UnittestLite.optionalSint64ExtensionLite, 106L)
+          setExtension(UnittestLite.optionalFixed32ExtensionLite, 107)
+          setExtension(UnittestLite.optionalFixed64ExtensionLite, 108L)
+          setExtension(UnittestLite.optionalSfixed32ExtensionLite, 109)
+          setExtension(UnittestLite.optionalSfixed64ExtensionLite, 110L)
+          setExtension(UnittestLite.optionalFloatExtensionLite, 111F)
+          setExtension(UnittestLite.optionalDoubleExtensionLite, 112.0)
+          setExtension(UnittestLite.optionalBoolExtensionLite, true)
+          setExtension(UnittestLite.optionalStringExtensionLite, "115")
+          setExtension(UnittestLite.optionalBytesExtensionLite, toBytes("116"))
+          setExtension(
+            UnittestLite.optionalGroupExtensionLite,
+            optionalGroupExtensionLite { a = 117 }
+          )
+          setExtension(
+            UnittestLite.optionalNestedMessageExtensionLite,
             TestAllTypesLiteKt.nestedMessage { bb = 118 }
-          this[UnittestLite.optionalForeignMessageExtensionLite] = foreignMessageLite { c = 119 }
-          this[UnittestLite.optionalImportMessageExtensionLite] =
+          )
+          setExtension(
+            UnittestLite.optionalForeignMessageExtensionLite,
+            foreignMessageLite { c = 119 }
+          )
+          setExtension(
+            UnittestLite.optionalImportMessageExtensionLite,
             ImportMessageLite.newBuilder().setD(120).build()
-          this[UnittestLite.optionalPublicImportMessageExtensionLite] =
+          )
+          setExtension(
+            UnittestLite.optionalPublicImportMessageExtensionLite,
             PublicImportMessageLite.newBuilder().setE(126).build()
-          this[UnittestLite.optionalLazyMessageExtensionLite] =
+          )
+          setExtension(
+            UnittestLite.optionalLazyMessageExtensionLite,
             TestAllTypesLiteKt.nestedMessage { bb = 127 }
-          this[UnittestLite.optionalUnverifiedLazyMessageExtensionLite] =
+          )
+          setExtension(
+            UnittestLite.optionalUnverifiedLazyMessageExtensionLite,
             TestAllTypesLiteKt.nestedMessage { bb = 128 }
-          this[UnittestLite.optionalNestedEnumExtensionLite] = NestedEnum.BAZ
-          this[UnittestLite.optionalForeignEnumExtensionLite] = ForeignEnumLite.FOREIGN_LITE_BAZ
-          this[UnittestLite.optionalImportEnumExtensionLite] = ImportEnumLite.IMPORT_LITE_BAZ
-          this[UnittestLite.optionalStringPieceExtensionLite] = "124"
-          this[UnittestLite.optionalCordExtensionLite] = "125"
+          )
+          setExtension(UnittestLite.optionalNestedEnumExtensionLite, NestedEnum.BAZ)
+          setExtension(
+            UnittestLite.optionalForeignEnumExtensionLite,
+            ForeignEnumLite.FOREIGN_LITE_BAZ
+          )
+          setExtension(UnittestLite.optionalImportEnumExtensionLite, ImportEnumLite.IMPORT_LITE_BAZ)
+          setExtension(UnittestLite.optionalStringPieceExtensionLite, "124")
+          setExtension(UnittestLite.optionalCordExtensionLite, "125")
           this[UnittestLite.repeatedInt32ExtensionLite].add(201)
           this[UnittestLite.repeatedInt64ExtensionLite].add(202L)
           this[UnittestLite.repeatedUint32ExtensionLite].add(203)
diff --git a/java/kotlin/src/test/kotlin/com/google/protobuf/Proto2Test.kt b/java/kotlin/src/test/kotlin/com/google/protobuf/Proto2Test.kt
index 5ca3403ff37d..71e500d03bb2 100644
--- a/java/kotlin/src/test/kotlin/com/google/protobuf/Proto2Test.kt
+++ b/java/kotlin/src/test/kotlin/com/google/protobuf/Proto2Test.kt
@@ -487,26 +487,26 @@ class Proto2Test {
           this[UnittestProto.repeatedImportEnumExtension] += ImportEnum.IMPORT_BAZ
           this[UnittestProto.repeatedStringPieceExtension] += "324"
           this[UnittestProto.repeatedCordExtension] += "325"
-          this[UnittestProto.defaultInt32Extension] = 401
-          this[UnittestProto.defaultInt64Extension] = 402L
-          this[UnittestProto.defaultUint32Extension] = 403
-          this[UnittestProto.defaultUint64Extension] = 404L
-          this[UnittestProto.defaultSint32Extension] = 405
-          this[UnittestProto.defaultSint64Extension] = 406L
-          this[UnittestProto.defaultFixed32Extension] = 407
-          this[UnittestProto.defaultFixed64Extension] = 408L
-          this[UnittestProto.defaultSfixed32Extension] = 409
-          this[UnittestProto.defaultSfixed64Extension] = 410L
-          this[UnittestProto.defaultFloatExtension] = 411F
-          this[UnittestProto.defaultDoubleExtension] = 412.0
-          this[UnittestProto.defaultBoolExtension] = false
-          this[UnittestProto.defaultStringExtension] = "415"
-          this[UnittestProto.defaultBytesExtension] = toBytes("416")
-          this[UnittestProto.defaultNestedEnumExtension] = NestedEnum.FOO
-          this[UnittestProto.defaultForeignEnumExtension] = ForeignEnum.FOREIGN_FOO
-          this[UnittestProto.defaultImportEnumExtension] = ImportEnum.IMPORT_FOO
-          this[UnittestProto.defaultStringPieceExtension] = "424"
-          this[UnittestProto.defaultCordExtension] = "425"
+          setExtension(UnittestProto.defaultInt32Extension, 401)
+          setExtension(UnittestProto.defaultInt64Extension, 402L)
+          setExtension(UnittestProto.defaultUint32Extension, 403)
+          setExtension(UnittestProto.defaultUint64Extension, 404L)
+          setExtension(UnittestProto.defaultSint32Extension, 405)
+          setExtension(UnittestProto.defaultSint64Extension, 406L)
+          setExtension(UnittestProto.defaultFixed32Extension, 407)
+          setExtension(UnittestProto.defaultFixed64Extension, 408L)
+          setExtension(UnittestProto.defaultSfixed32Extension, 409)
+          setExtension(UnittestProto.defaultSfixed64Extension, 410L)
+          setExtension(UnittestProto.defaultFloatExtension, 411F)
+          setExtension(UnittestProto.defaultDoubleExtension, 412.0)
+          setExtension(UnittestProto.defaultBoolExtension, false)
+          setExtension(UnittestProto.defaultStringExtension, "415")
+          setExtension(UnittestProto.defaultBytesExtension, toBytes("416"))
+          setExtension(UnittestProto.defaultNestedEnumExtension, NestedEnum.FOO)
+          setExtension(UnittestProto.defaultForeignEnumExtension, ForeignEnum.FOREIGN_FOO)
+          setExtension(UnittestProto.defaultImportEnumExtension, ImportEnum.IMPORT_FOO)
+          setExtension(UnittestProto.defaultStringPieceExtension, "424")
+          setExtension(UnittestProto.defaultCordExtension, "425")
           this[UnittestProto.oneofUint32Extension] = 601
           this[UnittestProto.oneofNestedMessageExtension] =
             TestAllTypesKt.nestedMessage { bb = 602 }
diff --git a/src/google/protobuf/compiler/java/message.cc b/src/google/protobuf/compiler/java/message.cc
index f23a79ceab11..2d51b25992b7 100644
--- a/src/google/protobuf/compiler/java/message.cc
+++ b/src/google/protobuf/compiler/java/message.cc
@@ -1437,8 +1437,7 @@ void ImmutableMessageGenerator::GenerateKotlinExtensions(
 
   printer->Print(
       "@kotlin.jvm.JvmSynthetic\n"
-      "@kotlin.PublishedApi\n"
-      "internal fun <T : kotlin.Any> setExtension(extension: "
+      "public fun <T : kotlin.Any> setExtension(extension: "
       "com.google.protobuf.ExtensionLite<$message$, T>, "
       "value: T) {\n"
       "  _builder.setExtension(extension, value)\n"
diff --git a/src/google/protobuf/compiler/java/message_lite.cc b/src/google/protobuf/compiler/java/message_lite.cc
index 45b6f11049d2..d6e480f82366 100644
--- a/src/google/protobuf/compiler/java/message_lite.cc
+++ b/src/google/protobuf/compiler/java/message_lite.cc
@@ -942,8 +942,7 @@ void ImmutableMessageLiteGenerator::GenerateKotlinExtensions(
 
   printer->Print(
       "@kotlin.jvm.JvmSynthetic\n"
-      "@kotlin.PublishedApi\n"
-      "internal fun <T : kotlin.Any> setExtension(extension: "
+      "public fun <T : kotlin.Any> setExtension(extension: "
       "com.google.protobuf.ExtensionLite<$message$, T>, "
       "value: T) {\n"
       "  _builder.setExtension(extension, value)\n"