Почему Proguard не работает при использовании minifyEnabled true?

Я пытаюсь запустить сборку Android с помощью gradle. Он работает нормально, пока я не минимизирую. Когда я включаю минимизацию (minifyEnabled true), сборка всегда завершается сбоем, потому что «не удалось создать прокси-класс для proguard.gradle.ProGuardTask».

WARNING [Project: :phone] Support for libraries with same package name is deprecated and will be removed in 1.0
running signingConfigs
running proguard

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring project ':phone'.
> Could not generate a proxy class for class proguard.gradle.ProGuardTask.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

раздел файла gradle, где я использую minify:

buildTypes {
        release {
            println "running proguard"
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-project.txt'
            signingConfig signingConfigs.release
        }
        debug {
            debuggable true
        }
    }

Просто нужна помощь, чтобы узнать, где искать... спасибо.

Полная трассировка стека

* Exception is:
org.gradle.api.ProjectConfigurationException: A problem occurred configuring project ':phone'.
        at org.gradle.configuration.project.LifecycleProjectEvaluator.addConfigurationFailure(LifecycleProjectEvaluator.java:91)
        at org.gradle.configuration.project.LifecycleProjectEvaluator.notifyAfterEvaluate(LifecycleProjectEvaluator.java:86)
        at org.gradle.configuration.project.LifecycleProjectEvaluator.evaluate(LifecycleProjectEvaluator.java:65)
        at org.gradle.api.internal.project.AbstractProject.evaluate(AbstractProject.java:504)
        at org.gradle.api.internal.project.AbstractProject.evaluate(AbstractProject.java:83)
        at org.gradle.execution.TaskPathProjectEvaluator.configureHierarchy(TaskPathProjectEvaluator.java:47)
        at org.gradle.configuration.DefaultBuildConfigurer.configure(DefaultBuildConfigurer.java:35)
        at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:129)
        at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:106)
        at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:86)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:80)
        at org.gradle.launcher.cli.ExecuteBuildAction.run(ExecuteBuildAction.java:33)
        at org.gradle.launcher.cli.ExecuteBuildAction.run(ExecuteBuildAction.java:24)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:36)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:26)
        at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:51)
        at org.gradle.internal.Actions$RunnableActionAdapter.execute(Actions.java:171)
        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:237)
        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:210)
        at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:35)
        at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:24)
        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:206)
        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:169)
        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:33)
        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:22)
        at org.gradle.launcher.Main.doAction(Main.java:33)
        at org.gradle.launcher.bootstrap.EntryPoint.run(EntryPoint.java:45)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBootstrap.java:54)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:35)
        at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
        at org.gradle.wrapper.BootstrapMainStarter.start(BootstrapMainStarter.java:33)
        at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:130)
        at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:48)
Caused by: org.gradle.api.GradleException: Could not generate a proxy class for class proguard.gradle.ProGuardTask.
        at org.gradle.api.internal.AbstractClassGenerator.generateUnderLock(AbstractClassGenerator.java:204)
        at org.gradle.api.internal.AbstractClassGenerator.generate(AbstractClassGenerator.java:67)
        at org.gradle.api.internal.project.taskfactory.TaskFactory.createTaskObject(TaskFactory.java:116)
        at org.gradle.api.internal.project.taskfactory.TaskFactory.createTask(TaskFactory.java:81)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory.createTask(AnnotationProcessingTaskFactory.java:99)
        at org.gradle.api.internal.project.taskfactory.DependencyAutoWireTaskFactory.createTask(DependencyAutoWireTaskFactory.java:39)
        at org.gradle.api.internal.tasks.DefaultTaskContainer.create(DefaultTaskContainer.java:52)
        at org.gradle.api.internal.tasks.DefaultTaskContainer.create(DefaultTaskContainer.java:83)
        at com.android.build.gradle.BasePlugin.createProguardTasks(BasePlugin.groovy:2776)
        at com.android.build.gradle.BasePlugin$createProguardTasks$31.callCurrent(Unknown Source)
        at com.android.build.gradle.BasePlugin.createPostCompilationTasks(BasePlugin.groovy:2021)
        at com.android.build.gradle.internal.variant.ApplicationVariantFactory.createTasks(ApplicationVariantFactory.java:189)
        at com.android.build.gradle.internal.VariantManager.createTasksForVariantData(VariantManager.java:274)
        at com.android.build.gradle.internal.VariantManager.createAndroidTasks(VariantManager.java:216)
        at com.android.build.gradle.internal.VariantManager$createAndroidTasks.call(Unknown Source)
        at com.android.build.gradle.BasePlugin.createAndroidTasks(BasePlugin.groovy:463)
        at com.android.build.gradle.BasePlugin$_createTasks_closure9.doCall(BasePlugin.groovy:408)
        at org.gradle.listener.ClosureBackedMethodInvocationDispatch.dispatch(ClosureBackedMethodInvocationDispatch.java:40)
        at org.gradle.listener.ClosureBackedMethodInvocationDispatch.dispatch(ClosureBackedMethodInvocationDispatch.java:25)
        at org.gradle.listener.BroadcastDispatch.dispatch(BroadcastDispatch.java:83)
        at org.gradle.listener.BroadcastDispatch.dispatch(BroadcastDispatch.java:31)
        at org.gradle.messaging.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:93)
        at com.sun.proxy.$Proxy13.afterEvaluate(Unknown Source)
        at org.gradle.configuration.project.LifecycleProjectEvaluator.notifyAfterEvaluate(LifecycleProjectEvaluator.java:79)
        ... 31 more
Caused by: java.lang.NoClassDefFoundError: proguard/ParseException
        at org.gradle.api.internal.AbstractClassGenerator.inspectType(AbstractClassGenerator.java:265)
        at org.gradle.api.internal.AbstractClassGenerator.inspectType(AbstractClassGenerator.java:220)
        at org.gradle.api.internal.AbstractClassGenerator.generateUnderLock(AbstractClassGenerator.java:98)
        ... 54 more
Caused by: java.lang.ClassNotFoundException: proguard.ParseException
        ... 57 more