diff --git a/README.md b/README.md
index 522c70aa30..719c55e7bb 100644
--- a/README.md
+++ b/README.md
@@ -3,11 +3,11 @@
 [![official JetBrains project](https://jb.gg/badges/official.svg)](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub)
 [![GitHub license](https://img.shields.io/badge/license-Apache%20License%202.0-blue.svg?style=flat)](https://www.apache.org/licenses/LICENSE-2.0)
 [![Download](https://api.bintray.com/packages/kotlin/kotlinx/kotlinx.coroutines/images/download.svg?version=1.4.2) ](https://bintray.com/kotlin/kotlinx/kotlinx.coroutines/1.4.2)
-[![Kotlin](https://img.shields.io/badge/kotlin-1.4.0-blue.svg?logo=kotlin)](http://kotlinlang.org)
+[![Kotlin](https://img.shields.io/badge/kotlin-1.4.20-blue.svg?logo=kotlin)](http://kotlinlang.org)
 [![Slack channel](https://img.shields.io/badge/chat-slack-green.svg?logo=slack)](https://kotlinlang.slack.com/messages/coroutines/)
 
 Library support for Kotlin coroutines with [multiplatform](#multiplatform) support.
-This is a companion version for Kotlin `1.4.0` release.
+This is a companion version for Kotlin `1.4.20` release.
 
 ```kotlin
 suspend fun main() = coroutineScope {
@@ -94,7 +94,7 @@ And make sure that you use the latest Kotlin version:
 
 ```xml
 <properties>
-    <kotlin.version>1.4.0</kotlin.version>
+    <kotlin.version>1.4.20</kotlin.version>
 </properties>
 ```
 
@@ -112,7 +112,7 @@ And make sure that you use the latest Kotlin version:
 
 ```groovy
 buildscript {
-    ext.kotlin_version = '1.4.0'
+    ext.kotlin_version = '1.4.20'
 }
 ```
 
@@ -138,7 +138,7 @@ And make sure that you use the latest Kotlin version:
 
 ```groovy
 plugins {
-    kotlin("jvm") version "1.4.0"
+    kotlin("jvm") version "1.4.20"
 }
 ```
 
diff --git a/build.gradle b/build.gradle
index 938d42e7a1..e4cacbfb07 100644
--- a/build.gradle
+++ b/build.gradle
@@ -203,6 +203,8 @@ configure(subprojects.findAll { !sourceless.contains(it.name) }) {
         kotlinOptions.freeCompilerArgs += experimentalAnnotations.collect { "-Xuse-experimental=" + it }
         kotlinOptions.freeCompilerArgs += "-progressive"
         kotlinOptions.freeCompilerArgs += "-XXLanguage:+InlineClasses"
+        // Disable KT-36770 for RxJava2 integration
+        kotlinOptions.freeCompilerArgs += "-XXLanguage:-ProhibitUsingNullableTypeParameterAgainstNotNullAnnotated"
         // Remove null assertions to get smaller bytecode on Android
         kotlinOptions.freeCompilerArgs += ["-Xno-param-assertions", "-Xno-receiver-assertions", "-Xno-call-assertions"]
     }
@@ -335,4 +337,4 @@ if (jvm_ir_enabled) {
             enabled = enabled && jvm_ir_api_check_enabled
         }
     }
-}
\ No newline at end of file
+}
diff --git a/gradle.properties b/gradle.properties
index cb039062f8..3c9fed6236 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -5,7 +5,7 @@
 # Kotlin
 version=1.4.2-SNAPSHOT
 group=org.jetbrains.kotlinx
-kotlin_version=1.4.0
+kotlin_version=1.4.20
 
 # Dependencies
 junit_version=4.12
diff --git a/gradle/publish-mpp-root-module-in-platform.gradle b/gradle/publish-mpp-root-module-in-platform.gradle
index 8bc0b502db..28068273c9 100644
--- a/gradle/publish-mpp-root-module-in-platform.gradle
+++ b/gradle/publish-mpp-root-module-in-platform.gradle
@@ -3,37 +3,40 @@
  */
 
 
-/*
- * Publish the platform JAR and POM so that consumers who depend on this module and can't read Gradle module metadata
- * can still get the platform artifact and transitive dependencies from the POM.
- *
- * See the full rationale here https://youtrack.jetbrains.com/issue/KMM-237#focus=streamItem-27-4115233.0-0
- */
-project.ext.publishPlatformArtifactsInRootModule = { platformPublication ->
-    def platformPomBuilder = null
+/** Publish the platform JAR and POM so that consumers who depend on this module and can't read Gradle module
+ metadata can still get the platform artifact and transitive dependencies from the POM: */
+project.ext.publishPlatformArtifactsInRootModule = { MavenPublication platformPublication ->
 
-    platformPublication.pom.withXml { platformPomBuilder = asString() }
+    XmlProvider platformXml = null
 
-    publishing.publications.kotlinMultiplatform  {
-        platformPublication.artifacts.forEach {
-            artifact(it)
-        }
+    platformPublication.pom.withXml { platformXml = it }
 
+    publishing.publications.kotlinMultiplatform {
         pom.withXml {
-            def pomStringBuilder = asString()
-            pomStringBuilder.setLength(0)
-            // The platform POM needs its artifact ID replaced with the artifact ID of the root module:
-            def platformPomString = platformPomBuilder.toString()
-            platformPomString.eachLine { line ->
-                if (!line.contains("<!--")) { // Remove the Gradle module metadata marker as it will be added anew
-                    pomStringBuilder.append(line.replace(platformPublication.artifactId, artifactId))
-                    pomStringBuilder.append("\n")
-                }
-            }
+            Node root = asNode()
+            // Remove the original content and add the content from the platform POM:
+            root.children().toList().each { root.remove(it as Node) }
+            platformXml.asNode().children().each { root.append(it as Node) }
+
+            // Adjust the self artifact ID, as it should match the root module's coordinates:
+            ((root.get("artifactId") as NodeList).get(0) as Node).setValue(artifactId)
+
+            // Set packaging to POM to indicate that there's no artifact:
+            root.appendNode("packaging", "pom")
+
+            // Remove the original platform dependencies and add a single dependency on the platform module:
+            Node dependencies = (root.get("dependencies") as NodeList).get(0) as Node
+            dependencies.children().toList().each { dependencies.remove(it as Node) }
+            Node singleDependency = dependencies.appendNode("dependency")
+            singleDependency.appendNode("groupId", platformPublication.groupId)
+            singleDependency.appendNode("artifactId", platformPublication.artifactId)
+            singleDependency.appendNode("version", platformPublication.version)
+            singleDependency.appendNode("scope", "compile")
         }
     }
 
-    tasks.matching { it.name == "generatePomFileForKotlinMultiplatformPublication"}.configureEach {
+    tasks.matching { it.name == "generatePomFileForKotlinMultiplatformPublication" }.configureEach {
         dependsOn(tasks["generatePomFileFor${platformPublication.name.capitalize()}Publication"])
     }
-}
\ No newline at end of file
+
+}
diff --git a/integration-testing/src/debugAgentTest/kotlin/PrecompiledDebugProbesTest.kt b/integration-testing/src/debugAgentTest/kotlin/PrecompiledDebugProbesTest.kt
index 5d799ee02f..2090d45471 100644
--- a/integration-testing/src/debugAgentTest/kotlin/PrecompiledDebugProbesTest.kt
+++ b/integration-testing/src/debugAgentTest/kotlin/PrecompiledDebugProbesTest.kt
@@ -36,4 +36,4 @@ class PrecompiledDebugProbesTest {
                         "ensure that classfile has major version equal to 50 (Java 6 compliance)")
         }
     }
-}
\ No newline at end of file
+}
diff --git a/js/example-frontend-js/build.gradle b/js/example-frontend-js/build.gradle
index 7abde63964..2bba6022ac 100644
--- a/js/example-frontend-js/build.gradle
+++ b/js/example-frontend-js/build.gradle
@@ -31,3 +31,24 @@ project.kotlin {
         }
     }
 }
+
+
+// Workaround for bug in 1.4.20 that will be fixed in 1.4.21, KT-43668
+tasks.withType(org.jetbrains.kotlin.gradle.targets.js.npm.tasks.KotlinPackageJsonTask) {
+    doFirst {
+        def producerField = it.class.superclass.getDeclaredMethod("getProducer")
+        producerField.setAccessible(true);
+        def producer = producerField.invoke(it)
+        def items = producer.fileCollectionDependencies
+        def list2 = new HashSet<FileCollectionDependency>()
+        for (FileCollectionDependency item : items) {
+            for (File file : item.files) {
+                if (!file.isFile()) {
+                    list2.add(item)
+                    break
+                }
+            }
+        }
+        items.removeAll(list2)
+    }
+}
diff --git a/kotlinx-coroutines-core/jvm/resources/DebugProbesKt.bin b/kotlinx-coroutines-core/jvm/resources/DebugProbesKt.bin
index 76ee41159d..2c44f7ec85 100644
Binary files a/kotlinx-coroutines-core/jvm/resources/DebugProbesKt.bin and b/kotlinx-coroutines-core/jvm/resources/DebugProbesKt.bin differ
diff --git a/kotlinx-coroutines-debug/test/DebugProbesTest.kt b/kotlinx-coroutines-debug/test/DebugProbesTest.kt
index 3b32db3a5a..01b2da0006 100644
--- a/kotlinx-coroutines-debug/test/DebugProbesTest.kt
+++ b/kotlinx-coroutines-debug/test/DebugProbesTest.kt
@@ -45,6 +45,7 @@ class DebugProbesTest : DebugTestBase() {
                         "\tat kotlinx.coroutines.DeferredCoroutine.await\$suspendImpl(Builders.common.kt)\n" +
                         "\tat kotlinx.coroutines.debug.DebugProbesTest.oneMoreNestedMethod(DebugProbesTest.kt)\n" +
                         "\tat kotlinx.coroutines.debug.DebugProbesTest.nestedMethod(DebugProbesTest.kt)\n" +
+                        "\tat kotlinx.coroutines.debug.DebugProbesTest\$testAsyncWithProbes\$1\$1.invokeSuspend(DebugProbesTest.kt:62)\n" +
                         "\t(Coroutine creation stacktrace)\n" +
                         "\tat kotlin.coroutines.intrinsics.IntrinsicsKt__IntrinsicsJvmKt.createCoroutineUnintercepted(IntrinsicsJvm.kt)\n" +
                         "\tat kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt)\n" +
@@ -76,6 +77,7 @@ class DebugProbesTest : DebugTestBase() {
                         "\tat kotlinx.coroutines.DeferredCoroutine.await\$suspendImpl(Builders.common.kt)\n" +
                         "\tat kotlinx.coroutines.debug.DebugProbesTest.oneMoreNestedMethod(DebugProbesTest.kt:71)\n" +
                         "\tat kotlinx.coroutines.debug.DebugProbesTest.nestedMethod(DebugProbesTest.kt:66)\n" +
+                        "\tat kotlinx.coroutines.debug.DebugProbesTest\$testAsyncWithSanitizedProbes\$1\$1.invokeSuspend(DebugProbesTest.kt:87)\n" +
                         "\t(Coroutine creation stacktrace)\n" +
                         "\tat kotlin.coroutines.intrinsics.IntrinsicsKt__IntrinsicsJvmKt.createCoroutineUnintercepted(IntrinsicsJvm.kt:116)\n" +
                         "\tat kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:23)\n" +
diff --git a/kotlinx-coroutines-debug/test/SanitizedProbesTest.kt b/kotlinx-coroutines-debug/test/SanitizedProbesTest.kt
index bf6cbdf10c..c897e2ed1a 100644
--- a/kotlinx-coroutines-debug/test/SanitizedProbesTest.kt
+++ b/kotlinx-coroutines-debug/test/SanitizedProbesTest.kt
@@ -87,7 +87,7 @@ class SanitizedProbesTest : DebugTestBase() {
                 "\tat kotlin.coroutines.intrinsics.IntrinsicsKt__IntrinsicsJvmKt.createCoroutineUnintercepted(IntrinsicsJvm.kt:116)",
 
             "Coroutine \"coroutine#2\":StandaloneCoroutine{Active}@1b68b9a4, state: SUSPENDED\n" +
-                "\tat definitely.not.kotlinx.coroutines.SanitizedProbesTest\$launchSelector\$1.invokeSuspend(SanitizedProbesTest.kt:143)\n" +
+                "\tat definitely.not.kotlinx.coroutines.SanitizedProbesTest\$launchSelector\$1\$1\$1.invokeSuspend(SanitizedProbesTest.kt)\n" +
                 "\t(Coroutine creation stacktrace)\n" +
                 "\tat kotlin.coroutines.intrinsics.IntrinsicsKt__IntrinsicsJvmKt.createCoroutineUnintercepted(IntrinsicsJvm.kt:116)\n" +
                 "\tat kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:25)\n" +