# Concurrent Modification Exception thrown when assembling **URL:** \ **Category:** Help/Discuss\ **Created:** [October 25, 2017, 11:39pm UTC](https://discuss.gradle.org/t/concurrent-modification-exception-thrown-when-assembling/24523 "2017-10-25T23:39:20Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![herriojr](https://avatars.discourse-cdn.com/v4/letter/h/96bed5/32.png) [@herriojr](https://discuss.gradle.org/u/herriojr)\ **Post date:** [October 25, 2017, 11:39pm UTC](https://discuss.gradle.org/t/concurrent-modification-exception-thrown-when-assembling/24523/1 "2017-10-25T23:39:20Z")
Hi, I’m trying to use composite builds with gradle 4.3-rc3, and I am getting a ConcurrentModificationException: 16:33:45.013 [INFO] [org.gradle.execution.taskgraph.DefaultTaskPlanExecutor] :my-library:mergeReleaseShaders (Thread[Task worker for ‘:family-and-friends-ui-lib’ Thread 4,5,main]) started. 16:33:45.015 [DEBUG] [org.gradle.internal.work.DefaultWorkerLeaseService] Worker lease root.1.338 completed (1 worker(s) in use) 16:33:45.015 [DEBUG] [org.gradle.internal.resources.AbstractTrackedResourceLock] Task worker for ‘:reservations-linking-ui-lib’ Thread 7: released lock on root.1.338 16:33:45.015 [DEBUG] [org.gradle.internal.resources.AbstractTrackedResourceLock] Task worker for ‘:reservations-linking-ui-lib’ Thread 7: released lock on :reservations-linking-ui-lib 16:33:45.015 [DEBUG] [org.gradle.internal.resources.AbstractTrackedResourceLock] Task worker for ‘:reservations-linking-ui-lib’ Thread 7: acquired lock on :reservations-linking-ui-lib 16:33:45.015 [DEBUG] [org.gradle.internal.work.DefaultWorkerLeaseService] Worker lease root.1.338 started (2 worker(s) in use). 16:33:45.015 [DEBUG] [org.gradle.internal.resources.AbstractTrackedResourceLock] Task worker for ‘:reservations-linking-ui-lib’ Thread 7: acquired lock on root.1.338 16:33:45.016 [INFO] [org.gradle.execution.taskgraph.DefaultTaskPlanExecutor] :reservations-linking-ui:mergeReleaseShaders (Thread[Task worker for ‘:reservations-linking-ui-lib’ Thread 7,5,main]) started. 16:33:45.016 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] FAILURE: Build failed with an exception. 16:33:45.016 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] 16:33:45.016 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] \* What went wrong: 16:33:45.017 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] java.util.ConcurrentModificationException (no error message) 16:33:45.018 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] 16:33:45.019 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] \* Exception is: 16:33:45.019 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] java.util.ConcurrentModificationException 16:33:45.019 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.composite.internal.DefaultIncludedBuildControllers.populateTaskGraphs(DefaultIncludedBuildControllers.java:72) 16:33:45.019 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.composite.internal.DefaultIncludedBuildControllers.startTaskExecution(DefaultIncludedBuildControllers.java:62) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.initialization.DefaultGradleLauncher$ExecuteTasks.run(DefaultGradleLauncher.java:311) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.initialization.DefaultGradleLauncher.runTasks(DefaultGradleLauncher.java:204) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:134) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.initialization.DefaultGradleLauncher.executeTasks(DefaultGradleLauncher.java:109) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.invocation.GradleBuildController$1.call(GradleBuildController.java:78) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.invocation.GradleBuildController$1.call(GradleBuildController.java:75) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.work.DefaultWorkerLeaseService.withLocks(DefaultWorkerLeaseService.java:152) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.invocation.GradleBuildController.doBuild(GradleBuildController.java:100) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.invocation.GradleBuildController.run(GradleBuildController.java:75) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.ExecuteBuildActionRunner.run(ExecuteBuildActionRunner.java:28) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.ValidatingBuildActionRunner.run(ValidatingBuildActionRunner.java:32) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner$1.run(RunAsBuildOperationBuildActionRunner.java:43) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner.run(RunAsBuildOperationBuildActionRunner.java:40) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.SubscribableBuildActionRunner.run(SubscribableBuildActionRunner.java:51) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:47) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:30) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.exec.BuildTreeScopeBuildActionExecuter.execute(BuildTreeScopeBuildActionExecuter.java:39) 16:33:45.020 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.exec.BuildTreeScopeBuildActionExecuter.execute(BuildTreeScopeBuildActionExecuter.java:25) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:80) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:53) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.ServicesSetupBuildActionExecuter.execute(ServicesSetupBuildActionExecuter.java:57) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.ServicesSetupBuildActionExecuter.execute(ServicesSetupBuildActionExecuter.java:32) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.GradleThreadBuildActionExecuter.execute(GradleThreadBuildActionExecuter.java:36) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.GradleThreadBuildActionExecuter.execute(GradleThreadBuildActionExecuter.java:25) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.ParallelismConfigurationBuildActionExecuter.execute(ParallelismConfigurationBuildActionExecuter.java:43) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.ParallelismConfigurationBuildActionExecuter.execute(ParallelismConfigurationBuildActionExecuter.java:29) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.StartParamsValidatingActionExecuter.execute(StartParamsValidatingActionExecuter.java:64) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.StartParamsValidatingActionExecuter.execute(StartParamsValidatingActionExecuter.java:29) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.SessionFailureReportingActionExecuter.execute(SessionFailureReportingActionExecuter.java:59) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.SessionFailureReportingActionExecuter.execute(SessionFailureReportingActionExecuter.java:44) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.SetupLoggingActionExecuter.execute(SetupLoggingActionExecuter.java:45) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.tooling.internal.provider.SetupLoggingActionExecuter.execute(SetupLoggingActionExecuter.java:30) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.ExecuteBuild.doBuild(ExecuteBuild.java:67) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:122) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.WatchForDisconnection.execute(WatchForDisconnection.java:37) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:122) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.ResetDeprecationLogger.execute(ResetDeprecationLogger.java:26) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:122) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.RequestStopIfSingleUsedDaemon.execute(RequestStopIfSingleUsedDaemon.java:34) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:122) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:74) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:72) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.util.Swapper.swap(Swapper.java:38) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.ForwardClientInput.execute(ForwardClientInput.java:72) 16:33:45.021 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:122) 16:33:45.022 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.LogAndCheckHealth.execute(LogAndCheckHealth.java:50) 16:33:45.022 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:122) 16:33:45.022 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.LogToClient.doBuild(LogToClient.java:62) 16:33:45.022 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36) 16:33:45.022 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:122) 16:33:45.022 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.EstablishBuildEnvironment.doBuild(EstablishBuildEnvironment.java:82) 16:33:45.023 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36) 16:33:45.023 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:122) 16:33:45.023 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.exec.StartBuildOrRespondWithBusy$1.run(StartBuildOrRespondWithBusy.java:50) 16:33:45.023 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.launcher.daemon.server.DaemonStateCoordinator$1.run(DaemonStateCoordinator.java:295) 16:33:45.023 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63) 16:33:45.023 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:46) 16:33:45.024 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:55) 16:33:45.024 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] 16:33:45.024 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] 16:33:45.024 [ERROR] [org.gradle.internal.buildevents.BuildExceptionReporter] \* Get more help at [https://help.gradle.org](https://help.gradle.org) 16:33:45.024 [ERROR] [org.gradle.internal.buildevents.BuildResultLogger] 16:33:45.024 [ERROR] [org.gradle.internal.buildevents.BuildResultLogger] BUILD FAILED in 14s then I just get the following in a loop: :35:21.369 [DEBUG] [org.gradle.launcher.daemon.server.Daemon] DaemonExpirationPeriodicCheck running 16:35:21.370 [DEBUG] [org.gradle.cache.internal.DefaultFileLockManager] Waiting to acquire shared lock on daemon addresses registry. 16:35:21.370 [DEBUG] [org.gradle.cache.internal.DefaultFileLockManager] Lock acquired on daemon addresses registry. 16:35:21.371 [DEBUG] [org.gradle.cache.internal.DefaultFileLockManager] Releasing lock on daemon addresses registry. 16:35:21.371 [DEBUG] [org.gradle.cache.internal.DefaultFileLockManager] Waiting to acquire shared lock on daemon addresses registry. 16:35:21.371 [DEBUG] [org.gradle.cache.internal.DefaultFileLockManager] Lock acquired on daemon addresses registry. 16:35:21.371 [DEBUG] [org.gradle.cache.internal.DefaultFileLockManager] Releasing lock on daemon addresses registry. 16:35:23.597 [DEBUG] [org.gradle.process.internal.health.memory.MemoryManager] Emitting OS memory status event {Total: 17179869184, Free: 5626077184} 16:35:23.597 [DEBUG] [org.gradle.launcher.daemon.server.health.LowMemoryDaemonExpirationStrategy] Received memory status update: {Total: 17179869184, Free: 5626077184} 16:35:23.597 [DEBUG] [org.gradle.process.internal.health.memory.MemoryManager] Emitting JVM memory status event {Maximum: 2386558976, Committed: 798490624} 16:35:28.599 [DEBUG] [org.gradle.process.internal.health.memory.MemoryManager] Emitting OS memory status event {Total: 17179869184, Free: 5626097664} 16:35:28.599 [DEBUG] [org.gradle.launcher.daemon.server.health.LowMemoryDaemonExpirationStrategy] Received memory status update: {Total: 17179869184, Free: 5626097664} 16:35:28.599 [DEBUG] [org.gradle.process.internal.health.memory.MemoryManager] Emitting JVM memory status event {Maximum: 2386558976, Committed: 798490624} I went to report a bug but I couldn’t find where to actually report in the issue tracker. ---
**Author:** ![jjustinic](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/jjustinic/32/9005_2.png) [@jjustinic](https://discuss.gradle.org/u/jjustinic)\ **Post date:** [October 26, 2017, 12:00am UTC](https://discuss.gradle.org/t/concurrent-modification-exception-thrown-when-assembling/24523/2 "2017-10-26T00:00:06Z")
> [@herriojr](#): > > I went to report a bug but I couldn’t find where to actually report in the issue tracker. Make sure you’re using [Issues · gradle/gradle · GitHub](https://github.com/gradle/gradle/issues) for new issues. You can’t report on the previous issue tracker any longer, but GitHub should have a large “New Issue” button at the top of the page. ---
**Author:** ![herriojr](https://avatars.discourse-cdn.com/v4/letter/h/96bed5/32.png) [@herriojr](https://discuss.gradle.org/u/herriojr)\ **Post date:** [October 26, 2017, 1:26am UTC](https://discuss.gradle.org/t/concurrent-modification-exception-thrown-when-assembling/24523/3 "2017-10-26T01:26:51Z")
Ah thank you, yeah, I didn’t go to the github one, I went to the old one.