diff --git a/plugins/jvm-abi-gen/src/org/jetbrains/kotlin/jvm/abi/JvmAbiMetadataProcessor.kt b/plugins/jvm-abi-gen/src/org/jetbrains/kotlin/jvm/abi/JvmAbiMetadataProcessor.kt
index 6e95df16337..c38c8a78c4c 100644
--- a/plugins/jvm-abi-gen/src/org/jetbrains/kotlin/jvm/abi/JvmAbiMetadataProcessor.kt
+++ b/plugins/jvm-abi-gen/src/org/jetbrains/kotlin/jvm/abi/JvmAbiMetadataProcessor.kt
@@ -46,6 +46,25 @@ fun abiMetadataProcessor(annotationVisitor: AnnotationVisitor): AnnotationVisito
                 pkg.removePrivateDeclarations()
                 KotlinClassMetadata.writeMultiFileClassPart(pkg, metadata.facadeClassName, metadataVersion, header.extraInt).annotationData
             }
+            null -> {
+                // TODO: maybe jvm-abi-gen should throw this exception by default, and not only in tests.
+                if (System.getProperty("idea.is.unit.test").toBoolean()) {
+                    val actual = "${metadataVersion[0]}.${metadataVersion[1]}"
+                    val expected = KotlinClassMetadata.COMPATIBLE_METADATA_VERSION.let { "${it[0]}.${it[1]}" }
+                    throw AssertionError(
+                        "jvm-abi-gen can't process class file with the new metadata version because the version of kotlinx-metadata-jvm " +
+                                "it depends on is too old.\n" +
+                                "Class file has metadata version $actual, but default metadata version of kotlinx-metadata-jvm is " +
+                                "$expected, so it can process class files with metadata version up to +1 from that (because of " +
+                                "Kotlin/JVM's one-version forward compatibility policy).\n" +
+                                "To fix this error, ensure that jvm-abi-gen depends on the latest version of kotlinx-metadata-jvm.\n" +
+                                "If this happens during the update of the default language version in the project, make sure that " +
+                                "a version of kotlinx-metadata-jvm has been published that supports this version, and update " +
+                                "\"versions.kotlinx-metadata-jvm\" in `gradle/versions.properties`."
+                    )
+                }
+                header
+            }
             else -> header
         }
 
diff --git a/plugins/jvm-abi-gen/test/org/jetbrains/kotlin/jvm/abi/BaseJvmAbiTest.kt b/plugins/jvm-abi-gen/test/org/jetbrains/kotlin/jvm/abi/BaseJvmAbiTest.kt
index 5a4c03f2abf..f25f4750b34 100644
--- a/plugins/jvm-abi-gen/test/org/jetbrains/kotlin/jvm/abi/BaseJvmAbiTest.kt
+++ b/plugins/jvm-abi-gen/test/org/jetbrains/kotlin/jvm/abi/BaseJvmAbiTest.kt
@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.jvm.abi
 
 import com.intellij.openapi.util.io.FileUtil
 import junit.framework.TestCase
+import kotlinx.metadata.jvm.KotlinClassMetadata
 import org.jetbrains.kotlin.cli.common.ExitCode
 import org.jetbrains.kotlin.cli.jvm.K2JVMCompiler
 import org.jetbrains.kotlin.codegen.CodegenTestUtil
@@ -81,7 +82,18 @@ abstract class BaseJvmAbiTest : TestCase() {
             ).toTypedArray()
             destination = compilation.destinationDir.canonicalPath
             noSourceDebugExtension = InTextDirectivesUtils.findStringWithPrefixes(directives, "// NO_SOURCE_DEBUG_EXTENSION") != null
-            useK2 = InTextDirectivesUtils.findStringWithPrefixes(directives, "// USE_K2") != null
+
+            if (InTextDirectivesUtils.findStringWithPrefixes(directives, "// USE_K2") != null) {
+                useK2 = true
+
+                // Force metadata version 1.9 to circumvent the fact that kotlinx-metadata-jvm 0.6.0 has default metadata version 1.8,
+                // so it can read/write metadata with versions up to and including 1.9, yet K2 has metadata version 2.0+.
+                // This hack can be removed once jvm-abi-gen depends on kotlinx-metadata-jvm that can read/write metadata version 2.0.
+                // Without this hack, CompileAgainstJvmAbiTestGenerated.testInlineClassWithPrivateConstructorK2 currently fails.
+                if (KotlinClassMetadata.COMPATIBLE_METADATA_VERSION.take(2) == listOf(1, 8)) {
+                    metadataVersion = "1.9"
+                }
+            }
         }
         val exitCode = compiler.exec(messageCollector, Services.EMPTY, args)
         if (exitCode != ExitCode.OK || messageCollector.errors.isNotEmpty()) {