Android build fails with R8

Question

Build is failing with the following error upon enabling R8 on android studio 3.4-RC3. Build is successful if android.enableR8=false

Undefined value encountered during compilation. This is typically caused by invalid dex input that uses a register that is not define on all control-flow paths leading to the use.

What is this undefined value and how do I fix this error?

> Task :app:transformClassesAndResourcesWithR8ForStageInternal FAILED
D8: Undefined value encountered during compilation. This is typically caused by invalid dex input that uses a register that is not define on all control-flow paths leading to the use.

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:transformClassesAndResourcesWithR8ForStageInternal'.
> com.android.tools.r8.CompilationFailedException: Compilation failed to complete

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

* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:transformClassesAndResourcesWithR8ForStageInternal'.
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$2.accept(ExecuteActionsTaskExecuter.java:121)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$2.accept(ExecuteActionsTaskExecuter.java:117)
        at org.gradle.internal.Try$Failure.ifSuccessfulOrElse(Try.java:184)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:110)
        at org.gradle.api.internal.tasks.execution.ResolveIncrementalChangesTaskExecuter.execute(ResolveIncrementalChangesTaskExecuter.java:84)
        at org.gradle.api.internal.tasks.execution.ResolveTaskOutputCachingStateExecuter.execute(ResolveTaskOutputCachingStateExecuter.java:92)
        at org.gradle.api.internal.tasks.execution.FinishSnapshotTaskInputsBuildOperationTaskExecuter.execute(FinishSnapshotTaskInputsBuildOperationTaskExecuter.java:51)
        at org.gradle.api.internal.tasks.execution.ResolveBuildCacheKeyExecuter.execute(ResolveBuildCacheKeyExecuter.java:103)
        at org.gradle.api.internal.tasks.execution.ResolveBeforeExecutionStateTaskExecuter.execute(ResolveBeforeExecutionStateTaskExecuter.java:75)
        at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
        at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:110)
        at org.gradle.api.internal.tasks.execution.ResolveBeforeExecutionOutputsTaskExecuter.execute(ResolveBeforeExecutionOutputsTaskExecuter.java:67)
        at org.gradle.api.internal.tasks.execution.StartSnapshotTaskInputsBuildOperationTaskExecuter.execute(StartSnapshotTaskInputsBuildOperationTaskExecuter.java:52)
        at org.gradle.api.internal.tasks.execution.ResolveAfterPreviousExecutionStateTaskExecuter.execute(ResolveAfterPreviousExecutionStateTaskExecuter.java:46)
        at org.gradle.api.internal.tasks.execution.CleanupStaleOutputsExecuter.execute(CleanupStaleOutputsExecuter.java:94)
        at org.gradle.api.internal.tasks.execution.FinalizePropertiesTaskExecuter.execute(FinalizePropertiesTaskExecuter.java:46)
        at org.gradle.api.internal.tasks.execution.ResolveTaskExecutionModeExecuter.execute(ResolveTaskExecutionModeExecuter.java:95)
        at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:57)
        at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:56)
        at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:36)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.executeTask(EventFiringTaskExecuter.java:63)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:49)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:46)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:416)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:406)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor$1.execute(DefaultBuildOperationExecutor.java:165)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:250)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:158)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:102)
        at org.gradle.internal.operations.DelegatingBuildOperationExecutor.call(DelegatingBuildOperationExecutor.java:36)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter.execute(EventFiringTaskExecuter.java:46)
        at org.gradle.execution.plan.LocalTaskNodeExecutor.execute(LocalTaskNodeExecutor.java:43)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:355)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:343)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:336)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:322)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker$1.execute(DefaultPlanExecutor.java:134)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker$1.execute(DefaultPlanExecutor.java:129)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.execute(DefaultPlanExecutor.java:202)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.executeNextNode(DefaultPlanExecutor.java:193)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.run(DefaultPlanExecutor.java:129)
        at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
        at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:46)
        at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:55)
Caused by: java.lang.RuntimeException: com.android.tools.r8.CompilationFailedException: Compilation failed to complete
        at com.android.builder.profile.Recorder$Block.handleException(Recorder.java:55)
        at com.android.builder.profile.ThreadRecorder.record(ThreadRecorder.java:104)
        at com.android.build.gradle.internal.pipeline.TransformTask.transform(TransformTask.java:230)
        at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:103)
        at org.gradle.api.internal.project.taskfactory.IncrementalTaskAction.doExecute(IncrementalTaskAction.java:73)
        at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:41)
        at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:28)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$4.run(ExecuteActionsTaskExecuter.java:337)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:402)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:394)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor$1.execute(DefaultBuildOperationExecutor.java:165)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:250)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:158)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:92)
        at org.gradle.internal.operations.DelegatingBuildOperationExecutor.run(DelegatingBuildOperationExecutor.java:31)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:326)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:311)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.access$200(ExecuteActionsTaskExecuter.java:75)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$TaskExecution.execute(ExecuteActionsTaskExecuter.java:158)
        at org.gradle.internal.execution.impl.steps.ExecuteStep.execute(ExecuteStep.java:46)
        at org.gradle.internal.execution.impl.steps.CancelExecutionStep.execute(CancelExecutionStep.java:34)
        at org.gradle.internal.execution.impl.steps.TimeoutStep.executeWithoutTimeout(TimeoutStep.java:69)
        at org.gradle.internal.execution.impl.steps.TimeoutStep.execute(TimeoutStep.java:49)
        at org.gradle.internal.execution.impl.steps.CatchExceptionStep.execute(CatchExceptionStep.java:34)
        at org.gradle.internal.execution.impl.steps.CreateOutputsStep.execute(CreateOutputsStep.java:49)
        at org.gradle.internal.execution.impl.steps.SnapshotOutputStep.execute(SnapshotOutputStep.java:42)
        at org.gradle.internal.execution.impl.steps.SnapshotOutputStep.execute(SnapshotOutputStep.java:28)
        at org.gradle.internal.execution.impl.steps.CacheStep.executeWithoutCache(CacheStep.java:136)
        at org.gradle.internal.execution.impl.steps.CacheStep.lambda$execute$5(CacheStep.java:86)
        at org.gradle.internal.execution.impl.steps.CacheStep.execute(CacheStep.java:85)
        at org.gradle.internal.execution.impl.steps.CacheStep.execute(CacheStep.java:37)
        at org.gradle.internal.execution.impl.steps.PrepareCachingStep.execute(PrepareCachingStep.java:33)
        at org.gradle.internal.execution.impl.steps.StoreSnapshotsStep.execute(StoreSnapshotsStep.java:38)
        at org.gradle.internal.execution.impl.steps.StoreSnapshotsStep.execute(StoreSnapshotsStep.java:23)
        at org.gradle.internal.execution.impl.steps.SkipUpToDateStep.executeBecause(SkipUpToDateStep.java:95)
        at org.gradle.internal.execution.impl.steps.SkipUpToDateStep.lambda$execute$0(SkipUpToDateStep.java:88)
        at org.gradle.internal.execution.impl.steps.SkipUpToDateStep.execute(SkipUpToDateStep.java:52)
        at org.gradle.internal.execution.impl.steps.SkipUpToDateStep.execute(SkipUpToDateStep.java:36)
        at org.gradle.internal.execution.impl.DefaultWorkExecutor.execute(DefaultWorkExecutor.java:34)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:109)
        ... 40 more
Caused by: com.android.tools.r8.CompilationFailedException: Compilation failed to complete
        at com.android.tools.r8.utils.ExceptionUtils.withCompilationHandler(ExceptionUtils.java:81)
        at com.android.tools.r8.utils.ExceptionUtils.withR8CompilationHandler(ExceptionUtils.java:50)
        at com.android.tools.r8.R8.runForTesting(R8.java:238)
        at com.android.tools.r8.R8.run(R8.java:148)
        at com.android.builder.dexing.R8Tool.runR8(r8Tool.kt:189)
        at com.android.build.gradle.internal.transforms.R8Transform.transform(R8Transform.kt:260)
        at com.android.build.gradle.internal.pipeline.TransformTask$2.call(TransformTask.java:239)
        at com.android.build.gradle.internal.pipeline.TransformTask$2.call(TransformTask.java:235)
        at com.android.builder.profile.ThreadRecorder.record(ThreadRecorder.java:102)
        ... 78 more
Caused by: com.android.tools.r8.utils.AbortException: Error: Undefined value encountered during compilation. This is typically caused by invalid dex input that uses a register that is not define on all control-flow paths leading to the use.
        at com.android.tools.r8.utils.Reporter.failIfPendingErrors(Reporter.java:101)
        at com.android.tools.r8.utils.Reporter.fatalError(Reporter.java:72)
        at com.android.tools.r8.utils.ExceptionUtils.withCompilationHandler(ExceptionUtils.java:66)
        ... 86 more

Answer 1

I was facing this same problem. I simply updated the gradle version from 3.4.0 to the latest 3.4.2 and it worked.

Answer 2

I just had the same issue and I fixed it by specifying a special release version

in your project's build.gradle

repositories {
        google()
        jcenter()
        repositories {
            maven {
                url "http://storage.googleapis.com/r8-releases/raw/master"
            }
        }

    }

dependencies {
    classpath 'com.android.tools:r8:1.6.84'  // Must be before the Gradle Plugin for Android.
    classpath 'com.android.tools.build:gradle:3.6.3'
}