Kotlin plugin error: failed to create proxy class for class org.jetbrains.kotlin.gradle.tasks.KotlinCompile

Question

An error occurred while trying to start the gradle task. I can’t understand what else is required or what is the error. The project I'm working on has several subprojects, so I have the main build.gradle. A bug for the subproject where I wanted to try Kotlin.

* Where: Build file '/home/oracle/bnc/KotlinHandler/build.gradle' line: 13 * What went wrong: A problem occurred evaluating root project 'KotlinHandler'. > Failed to apply plugin [id 'kotlin'] > Could not generate a proxy class for class org.jetbrains.kotlin.gradle.tasks.KotlinCompile. 

Here is my build.gradle for the module with the error (subproject).

 buildscript { ext.kotlin_version = '1.1.2-2' repositories { mavenCentral() } dependencies { classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" } } apply plugin: 'kotlin' repositories { mavenCentral() } dependencies { compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version" } 

Here is Pastebin build.gradle , which is quite large, due to all the tasks in it

Added --debug output after changing jdk to 1.8 and compile dependency to compile "org.jetbrains.kotlin:kotlin-stdlib-jre8

Answer 1

start kotlin 1.1.2 JDK below 1.8 is no longer supported by the kotlin compiler, as in the 1.1.2 blog post :

The Kotlin compiler now requires the launch of JDK 8. You should not notice any changes, since most other Java development tools, such as Gradle and the Android toolchain, also require JDK 8, so you almost certainly already installed it. For code generated by the compiler, Java 1.6 compatibility is still the default, and we do not plan to abandon support for creating Java 1.6 compatible bytecode.

Answer 2

In my case, this was due to the fact that I was running gradle with java 1.7, and it looks like the plugin was compiled only for version 1.8:

 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] Caused by: org.gradle.api.internal.plugins.PluginApplicationException: Failed to apply plugin [id 'kotlin'] 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.DefaultPluginManager.doApply(DefaultPluginManager.java:153) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.DefaultPluginManager.apply(DefaultPluginManager.java:112) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.applyType(DefaultObjectConfigurationAction.java:113) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.access$200(DefaultObjectConfigurationAction.java:36) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction$3.run(DefaultObjectConfigurationAction.java:80) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.execute(DefaultObjectConfigurationAction.java:136) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.project.AbstractPluginAware.apply(AbstractPluginAware.java:46) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.project.ProjectScript.apply(ProjectScript.java:34) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.Script$apply$1.callCurrent(Unknown Source) 16:48:42.742 [ERROR] [org.gradle.BuildExceptionReporter] at build_4u37tyfuy0k7d4zd8vsk5lx9d.run(build.gradle:17) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.groovy.scripts.internal.DefaultScriptRunnerFactory$ScriptRunnerImpl.run(DefaultScriptRunnerFactory.java:91) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] ... 63 more 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] Caused by: org.gradle.api.GradleException: Could not generate a proxy class for class org.jetbrains.kotlin.gradle.tasks.KotlinCompile. 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.AbstractClassGenerator.generateUnderLock(AbstractClassGenerator.java:201) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.AbstractClassGenerator.generate(AbstractClassGenerator.java:64) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.project.taskfactory.TaskFactory.create(TaskFactory.java:115) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.project.taskfactory.TaskFactory.createTask(TaskFactory.java:77) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory.createTask(AnnotationProcessingTaskFactory.java:101) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.project.taskfactory.DependencyAutoWireTaskFactory.createTask(DependencyAutoWireTaskFactory.java:39) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.tasks.DefaultTaskContainer.create(DefaultTaskContainer.java:62) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.tasks.DefaultTaskContainer.create(DefaultTaskContainer.java:97) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.tasks.KotlinTasksProvider.createKotlinJVMTask(TasksProvider.kt:26) 16:48:42.743 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.Kotlin2JvmSourceSetProcessor.doCreateTask(KotlinPlugin.kt:111) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.Kotlin2JvmSourceSetProcessor.doCreateTask(KotlinPlugin.kt:93) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.KotlinSourceSetProcessor.createKotlinCompileTask(KotlinPlugin.kt:83) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.KotlinSourceSetProcessor.<init>(KotlinPlugin.kt:56) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.Kotlin2JvmSourceSetProcessor.<init>(KotlinPlugin.kt:101) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.KotlinPlugin.buildSourceSetProcessor$kotlin_gradle_plugin_main(KotlinPlugin.kt:302) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.KotlinPlugin.buildSourceSetProcessor$kotlin_gradle_plugin_main(KotlinPlugin.kt:295) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.AbstractKotlinPlugin$configureSourceSetDefaults$1.execute(KotlinPlugin.kt:279) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.AbstractKotlinPlugin$configureSourceSetDefaults$1.execute(KotlinPlugin.kt:256) 16:48:42.744 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.DefaultDomainObjectCollection.all(DefaultDomainObjectCollection.java:110) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.AbstractKotlinPlugin.configureSourceSetDefaults(KotlinPlugin.kt:278) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.AbstractKotlinPlugin.apply(KotlinPlugin.kt:269) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.KotlinPlugin.apply(KotlinPlugin.kt:306) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.KotlinPlugin.apply(KotlinPlugin.kt:295) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.KotlinBasePluginWrapper.apply(KotlinPluginWrapper.kt:46) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.jetbrains.kotlin.gradle.plugin.KotlinBasePluginWrapper.apply(KotlinPluginWrapper.kt:34) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.ImperativeOnlyPluginApplicator.applyImperative(ImperativeOnlyPluginApplicator.java:35) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.RuleBasedPluginApplicator.applyImperative(RuleBasedPluginApplicator.java:43) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.plugins.DefaultPluginManager.doApply(DefaultPluginManager.java:137) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] ... 73 more 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] Caused by: java.lang.UnsupportedClassVersionError: org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments : Unsupported major.minor version 52.0 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.internal.reflect.ClassInspector.inspectClass(ClassInspector.java:67) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.internal.reflect.ClassInspector.visitGraph(ClassInspector.java:51) 16:48:42.745 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.internal.reflect.ClassInspector.inspect(ClassInspector.java:31) 16:48:42.746 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.AbstractClassGenerator.inspectType(AbstractClassGenerator.java:260) 16:48:42.746 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.AbstractClassGenerator.inspectType(AbstractClassGenerator.java:216) 16:48:42.746 [ERROR] [org.gradle.BuildExceptionReporter] at org.gradle.api.internal.AbstractClassGenerator.generateUnderLock(AbstractClassGenerator.java:95) 

Related tickets: https://youtrack.jetbrains.com/issue/KT-17866 and https://youtrack.jetbrains.com/issue/KT-17297

Answer 3

Try adding jcenter() repo to the buildscript repository and update the kotlin version.

 buildscript { ext.kotlin_version = '1.1.2-4' repositories { mavenCentral() jcenter() } dependencies { classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" } } apply plugin: "kotlin" repositories { mavenCentral() jcenter() } dependencies { compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version" } 

If you configure JDK 7 or JDK 8, you can use the extended versions of the Kotlin standard library, which contain additional extension functions for the APIs added to new versions of the JDK. Instead of kotlin-stdlib, use one of the following dependencies:

 compile "org.jetbrains.kotlin:kotlin-stdlib-jre7" compile "org.jetbrains.kotlin:kotlin-stdlib-jre8"