android - Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease

Question

I am trying to export apk and I want to enable Proguard but it throwing below error. I read so many answers and tried but didn't worked. Getting below error:

Warning:Exception while processing task java.io.IOException: java.lang.NullPointerException 
Error:Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease

StackTrace:

:app:transformClassesAndResourcesWithProguardForRelease
ProGuard, version 5.2.1
Warning: Exception while processing task java.io.IOException: java.lang.NullPointerException
:app:transformClassesAndResourcesWithProguardForRelease FAILED

FAILURE: Build failed with an exception.


* What went wrong:
Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease'.
> Job failed, see logs for details

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


* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease'.
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:69)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)
        at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:35)
        at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:66)
        at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
        at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:52)
        at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
        at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:53)
        at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:203)
        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:185)
        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(AbstractTaskPlanExecutor.java:66)
        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPlanExecutor.java:50)
        at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:25)
        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:110)
        at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:37)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37)
        at org.gradle.execution.DefaultBuildExecuter.access$000(DefaultBuildExecuter.java:23)
        at org.gradle.execution.DefaultBuildExecuter$1.proceed(DefaultBuildExecuter.java:43)
        at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:30)
        at org.gradle.initialization.DefaultGradleLauncher$4.run(DefaultGradleLauncher.java:153)
        at org.gradle.internal.Factories$1.create(Factories.java:22)
        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91)
        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:53)
        at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:150)
        at org.gradle.initialization.DefaultGradleLauncher.access$200(DefaultGradleLauncher.java:32)
        at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:98)
        at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:92)
        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91)
        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:63)
        at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:92)
        at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:83)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:99)
        at org.gradle.tooling.internal.provider.ExecuteBuildActionRunner.run(ExecuteBuildActionRunner.java:28)
        at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:48)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:30)
        at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:81)
        at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:46)
        at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.execute(DaemonUsageSuggestingBuildActionExecuter.java:51)
        at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.execute(DaemonUsageSuggestingBuildActionExecuter.java:28)
        at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:43)
        at org.gradle.internal.Actions$RunnableActionAdapter.execute(Actions.java:173)
        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:239)
        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:212)
        at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:35)
        at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:24)
        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:33)
        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:22)
        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:205)
        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:169)
        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:55)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:36)
        at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
        at org.gradle.wrapper.BootstrapMainStarter.start(BootstrapMainStarter.java:30)
        at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:129)
        at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)
Caused by: java.lang.RuntimeException: Job failed, see logs for details
        at com.android.build.gradle.internal.transforms.ProGuardTransform.transform(ProGuardTransform.java:196)
        at com.android.build.gradle.internal.pipeline.TransformTask$2.call(TransformTask.java:178)
        at com.android.build.gradle.internal.pipeline.TransformTask$2.call(TransformTask.java:174)
        at com.android.builder.profile.ThreadRecorder.record(ThreadRecorder.java:156)
        at com.android.build.gradle.internal.pipeline.TransformTask.transform(TransformTask.java:173)
        at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:75)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$IncrementalTaskAction.doExecute(AnnotationProcessingTaskFactory.java:245)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:221)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$IncrementalTaskAction.execute(AnnotationProcessingTaskFactory.java:232)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:210)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
        ... 60 more
Caused by: java.io.IOException: java.lang.NullPointerException
        at com.android.build.gradle.internal.transforms.ProGuardTransform.doMinification(ProGuardTransform.java:283)
        at com.android.build.gradle.internal.transforms.ProGuardTransform.access$000(ProGuardTransform.java:63)
        at com.android.build.gradle.internal.transforms.ProGuardTransform$1.run(ProGuardTransform.java:173)
        at com.android.builder.tasks.Job.runTask(Job.java:49)
        at com.android.build.gradle.tasks.SimpleWorkQueue$EmptyThreadContext.runTask(SimpleWorkQueue.java:41)
        at com.android.builder.tasks.WorkQueue.run(WorkQueue.java:223)
Caused by: java.lang.NullPointerException
        at proguard.util.FixedStringMatcher.matches(FixedStringMatcher.java:52)
        at proguard.util.OrMatcher.matches(OrMatcher.java:46)
        at proguard.classfile.util.WarningPrinter.accepts(WarningPrinter.java:89)
        at proguard.classfile.util.WarningPrinter.print(WarningPrinter.java:77)
        at proguard.KeepClassMemberChecker.checkClassSpecifications(KeepClassMemberChecker.java:76)
        at proguard.ConfigurationChecker.check(ConfigurationChecker.java:136)
        at proguard.ProGuard.execute(ProGuard.java:73)
        at com.android.build.gradle.internal.transforms.BaseProguardAction.runProguard(BaseProguardAction.java:54)
        at com.android.build.gradle.internal.transforms.ProGuardTransform.doMinification(ProGuardTransform.java:254)
        ... 5 more

Gradle file:

buildscript {
repositories {
    maven { url 'https://maven.fabric.io/public' }
   }

dependencies {
    classpath 'io.fabric.tools:gradle:1.+'
   }
}

apply plugin: 'com.android.application'
apply plugin: 'io.fabric'

repositories {
    maven { url 'https://maven.fabric.io/public' }
}

android {
compileSdkVersion 25
buildToolsVersion "25"

defaultConfig {
    applicationId "package_name"
    minSdkVersion 14
    targetSdkVersion 25
    versionCode 22
    versionName "2.3.1"
    multiDexEnabled true
}
buildTypes {
    release {
        minifyEnabled true
        shrinkResources true
        debuggable false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        buildConfigField "String", "BASE_URL", ""http://release.com/""
                }
    debug {
        testCoverageEnabled false
        minifyEnabled false
        shrinkResources false
        debuggable true
        versionNameSuffix '-dev'
        applicationIdSuffix '.dev'

        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        buildConfigField "String", "BASE_URL", ""http://test.com/""
        jackOp

Answer 1

add the below to your ProGuard rules

-ignorewarnings

-keep class * {
    public private *;
}

and rebuild your project.