diff --git a/generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt b/generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt
index 717858f1e43..f73cb2a906c 100644
--- a/generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt
+++ b/generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt
@@ -392,7 +392,7 @@ fun main(args: Array<String>) {
                 model("kotlinRunner")
             }
 
-            testClass<AbstractIrKotlinKaptContextTest>(annotations = annotations) {
+            testClass<AbstractIrKotlinKaptContextTest> {
                 model("kotlinRunner")
             }
 
diff --git a/plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/annotationProcessing.kt b/plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/annotationProcessing.kt
index 3d2d687ce87..f0c244bcba6 100644
--- a/plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/annotationProcessing.kt
+++ b/plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/annotationProcessing.kt
@@ -304,7 +304,7 @@ fun KaptContext.parseJavaFiles(javaSourceFiles: List<File>): JavacList<JCTree.JC
 }
 
 private fun KaptContext.initModulesIfNeeded(files: JavacList<JCTree.JCCompilationUnit>): JavacList<JCTree.JCCompilationUnit> {
-    if (isJava9OrLater()) {
+    if (files.isNotEmpty() && isJava9OrLater()) {
         val initModulesMethod = compiler.javaClass.getMethod("initModules", JavacList::class.java)
 
         @Suppress("UNCHECKED_CAST")
diff --git a/plugins/kapt3/kapt3-compiler/build.gradle.kts b/plugins/kapt3/kapt3-compiler/build.gradle.kts
index f3f0495cdfd..8e6d0f6deb7 100644
--- a/plugins/kapt3/kapt3-compiler/build.gradle.kts
+++ b/plugins/kapt3/kapt3-compiler/build.gradle.kts
@@ -64,6 +64,7 @@ testsJar {}
 kaptTestTask("test", JavaLanguageVersion.of(8))
 kaptTestTask("testJdk11", JavaLanguageVersion.of(11))
 kaptTestTask("testJdk17", JavaLanguageVersion.of(17))
+kaptTestTask("testJdk21", JavaLanguageVersion.of(21))
 
 fun Project.kaptTestTask(name: String, javaLanguageVersion: JavaLanguageVersion) {
     val service = extensions.getByType<JavaToolchainService>()
diff --git a/plugins/kapt3/kapt3-compiler/test/org/jetbrains/kotlin/kapt3/test/runners/AbstractClassFileToSourceStubConverterTest.kt b/plugins/kapt3/kapt3-compiler/test/org/jetbrains/kotlin/kapt3/test/runners/AbstractClassFileToSourceStubConverterTest.kt
index 9540f1c15b9..ad4f4c6c8db 100644
--- a/plugins/kapt3/kapt3-compiler/test/org/jetbrains/kotlin/kapt3/test/runners/AbstractClassFileToSourceStubConverterTest.kt
+++ b/plugins/kapt3/kapt3-compiler/test/org/jetbrains/kotlin/kapt3/test/runners/AbstractClassFileToSourceStubConverterTest.kt
@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.kapt3.test.runners
 
+import org.jetbrains.kotlin.kapt3.base.util.doOpenInternalPackagesIfRequired
 import org.jetbrains.kotlin.kapt3.test.JvmCompilerWithKaptFacade
 import org.jetbrains.kotlin.kapt3.test.KaptContextBinaryArtifact
 import org.jetbrains.kotlin.kapt3.test.KaptEnvironmentConfigurator
@@ -26,6 +27,10 @@ import org.jetbrains.kotlin.test.services.configuration.JvmEnvironmentConfigurat
 abstract class AbstractClassFileToSourceStubConverterTestBase(
     targetBackend: TargetBackend
 ) : AbstractKotlinCompilerWithTargetBackendTest(targetBackend) {
+    init {
+        doOpenInternalPackagesIfRequired()
+    }
+
     override fun TestConfigurationBuilder.configuration() {
         globalDefaults {
             frontend = FrontendKinds.ClassicFrontend
diff --git a/plugins/kapt3/kapt3-compiler/test/org/jetbrains/kotlin/kapt3/test/runners/AbstractKotlinKaptContextTest.kt b/plugins/kapt3/kapt3-compiler/test/org/jetbrains/kotlin/kapt3/test/runners/AbstractKotlinKaptContextTest.kt
index 9efef880d01..1eba7fea1ca 100644
--- a/plugins/kapt3/kapt3-compiler/test/org/jetbrains/kotlin/kapt3/test/runners/AbstractKotlinKaptContextTest.kt
+++ b/plugins/kapt3/kapt3-compiler/test/org/jetbrains/kotlin/kapt3/test/runners/AbstractKotlinKaptContextTest.kt
@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.kapt3.test.runners
 
+import org.jetbrains.kotlin.kapt3.base.util.doOpenInternalPackagesIfRequired
 import org.jetbrains.kotlin.kapt3.test.*
 import org.jetbrains.kotlin.kapt3.test.KaptTestDirectives.MAP_DIAGNOSTIC_LOCATIONS
 import org.jetbrains.kotlin.kapt3.test.handlers.KaptContextHandler
@@ -20,6 +21,10 @@ import org.jetbrains.kotlin.test.services.configuration.JvmEnvironmentConfigurat
 abstract class AbstractKotlinKaptContextTestBase(
     targetBackend: TargetBackend
 ) : AbstractKotlinCompilerWithTargetBackendTest(targetBackend) {
+    init {
+        doOpenInternalPackagesIfRequired()
+    }
+
     override fun TestConfigurationBuilder.configuration() {
         globalDefaults {
             frontend = FrontendKinds.ClassicFrontend
diff --git a/plugins/kapt3/kapt3-compiler/tests-gen/org/jetbrains/kotlin/kapt3/test/runners/IrKotlinKaptContextTestGenerated.java b/plugins/kapt3/kapt3-compiler/tests-gen/org/jetbrains/kotlin/kapt3/test/runners/IrKotlinKaptContextTestGenerated.java
index 649e0eb538f..c5dabde4533 100644
--- a/plugins/kapt3/kapt3-compiler/tests-gen/org/jetbrains/kotlin/kapt3/test/runners/IrKotlinKaptContextTestGenerated.java
+++ b/plugins/kapt3/kapt3-compiler/tests-gen/org/jetbrains/kotlin/kapt3/test/runners/IrKotlinKaptContextTestGenerated.java
@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.kapt3.test.runners;
 
 import com.intellij.testFramework.TestDataPath;
 import org.jetbrains.kotlin.test.util.KtTestUtil;
-import org.junit.jupiter.api.Tag;
 import org.jetbrains.kotlin.test.TargetBackend;
 import org.jetbrains.kotlin.test.TestMetadata;
 import org.junit.jupiter.api.Nested;
@@ -20,7 +19,6 @@ import java.util.regex.Pattern;
 @SuppressWarnings("all")
 @TestMetadata("plugins/kapt3/kapt3-compiler/testData/kotlinRunner")
 @TestDataPath("$PROJECT_ROOT")
-@Tag("IgnoreJDK11")
 public class IrKotlinKaptContextTestGenerated extends AbstractIrKotlinKaptContextTest {
     @Test
     public void testAllFilesPresentInKotlinRunner() throws Exception {
diff --git a/plugins/kapt4/build.gradle.kts b/plugins/kapt4/build.gradle.kts
index 3fa1929c7ca..d39ccbebd2f 100644
--- a/plugins/kapt4/build.gradle.kts
+++ b/plugins/kapt4/build.gradle.kts
@@ -56,6 +56,7 @@ testsJar {}
 kaptTestTask("test", JavaLanguageVersion.of(8))
 kaptTestTask("testJdk11", JavaLanguageVersion.of(11))
 kaptTestTask("testJdk17", JavaLanguageVersion.of(17))
+kaptTestTask("testJdk21", JavaLanguageVersion.of(21))
 
 fun Project.kaptTestTask(name: String, javaLanguageVersion: JavaLanguageVersion) {
     val service = extensions.getByType<JavaToolchainService>()
diff --git a/plugins/kapt4/test/org/jetbrains/kotlin/kapt4/AbstractKotlinKaptContextTestBase.kt b/plugins/kapt4/test/org/jetbrains/kotlin/kapt4/AbstractKotlinKapt4ContextTestBase.kt
similarity index 93%
rename from plugins/kapt4/test/org/jetbrains/kotlin/kapt4/AbstractKotlinKaptContextTestBase.kt
rename to plugins/kapt4/test/org/jetbrains/kotlin/kapt4/AbstractKotlinKapt4ContextTestBase.kt
index e14c8934b06..418f1bf72c6 100644
--- a/plugins/kapt4/test/org/jetbrains/kotlin/kapt4/AbstractKotlinKaptContextTestBase.kt
+++ b/plugins/kapt4/test/org/jetbrains/kotlin/kapt4/AbstractKotlinKapt4ContextTestBase.kt
@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.kapt4
 
+import org.jetbrains.kotlin.kapt3.base.util.doOpenInternalPackagesIfRequired
 import org.jetbrains.kotlin.kapt3.test.*
 import org.jetbrains.kotlin.kapt3.test.KaptTestDirectives.MAP_DIAGNOSTIC_LOCATIONS
 import org.jetbrains.kotlin.platform.jvm.JvmPlatforms
@@ -22,6 +23,10 @@ open class AbstractKotlinKapt4ContextTest : AbstractKotlinKapt4ContextTestBase(T
 abstract class AbstractKotlinKapt4ContextTestBase(
     targetBackend: TargetBackend
 ) : AbstractKotlinCompilerWithTargetBackendTest(targetBackend) {
+    init {
+        doOpenInternalPackagesIfRequired()
+    }
+
     override fun TestConfigurationBuilder.configuration() {
         globalDefaults {
             frontend = FrontendKinds.FIR