Hey @mtoanhcm, I was wondering if I could get more details about the crash. I found where the code is crashing, but I don't have a reliable way to reproduce the crash or test a possible fix so I'd like a little bit more information. What version of Android and Unity are you using, and on what device? Does the crash happen consistently? Do you have a minimal reproduction case?

Hi @alexames , I'm using Unity 2018.1.6f1, I cannot reproduction this bug, it does not usually happen (about 3% user). Bug happend in android version 5,6,7,8 and happen most in samsung device (54%). I send you my log from fabric, hope this help

`

Crashlytics - plaintext stacktrace downloaded by Khanh Nguyen at Tue, 17 Jul 2018 02:24:45 GMT

URL: https://fabric.io/wolffun/android/apps/com.obuut.tankio/issues/5a58e21f8cb3c2fa63b46a90?time=last-ninety-days/sessions/5B4D477A0325000143D609A5E63A8CC1_DNE_0_v2

Organization: Wolffun

Platform: android

Application: TankRaid

Version: 2.40 (144)

Bundle Identifier: com.obuut.tankio

Issue #: 5302

Issue ID: 5a58e21f8cb3c2fa63b46a90

Session ID: 5B4D477A0325000143D609A5E63A8CC1_DNE_0_v2

Date: 2018-07-17T01:34:00Z

OS Version: 6.0.1

Device: Galaxy S5

RAM Free: 24.9%

Disk Free: 26.9%

Fatal Exception: java.lang.Error: FATAL EXCEPTION [main]
Unity version : 2018.1.6f1
Device model : samsung SM-G900S
Device fingerprint: samsung/klteskt/klteskt:6.0.1/MMB29M/G900SKSU1CPL5:user/release-keys

Caused by java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
at com.google.firebase.app.internal.cpp.GoogleApiAvailabilityHelper$2$1.run(GoogleApiAvailabilityHelper.java:113)
at java.lang.Thread.run(Thread.java:818)
at com.google.firebase.app.internal.cpp.GoogleApiAvailabilityHelper$2.onDismiss(GoogleApiAvailabilityHelper.java:151)
at android.app.Dialog$ListenersHandler.handleMessage(Dialog.java:1533)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7224)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

#0. AsyncTask #4
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:410)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#1. Queue
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.PriorityBlockingQueue.take(PriorityBlockingQueue.java:510)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.performOperation(DependencyPriorityBlockingQueue.java:197)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.get(DependencyPriorityBlockingQueue.java:236)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:65)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:46)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#2. UnityMain
at android.os.MessageQueue.nativePollOnce(MessageQueue.java)
at android.os.MessageQueue.next(MessageQueue.java:323)
at android.os.Looper.loop(Looper.java:143)
at com.unity3d.player.UnityPlayer$e.run(Unknown Source)

#3. HeapTaskDaemon
at dalvik.system.VMRuntime.runHeapTasks(VMRuntime.java)
at java.lang.Daemons$HeapTaskDaemon.run(Daemons.java:370)
at java.lang.Thread.run(Thread.java:818)

#4. Queue
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.PriorityBlockingQueue.take(PriorityBlockingQueue.java:510)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.performOperation(DependencyPriorityBlockingQueue.java:197)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.get(DependencyPriorityBlockingQueue.java:236)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:65)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:46)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#5. ReferenceQueueDaemon
at java.lang.Object.wait(Object.java)
at java.lang.Daemons$ReferenceQueueDaemon.run(Daemons.java:162)
at java.lang.Thread.run(Thread.java:818)

#6. Queue
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.PriorityBlockingQueue.take(PriorityBlockingQueue.java:510)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.performOperation(DependencyPriorityBlockingQueue.java:197)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.get(DependencyPriorityBlockingQueue.java:236)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:65)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:46)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#7. pool-9-thread-1
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:410)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#8. FinalizerDaemon
at java.lang.Object.wait(Object.java)
at java.lang.Object.wait(Object.java:423)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:101)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:72)
at java.lang.Daemons$FinalizerDaemon.run(Daemons.java:200)
at java.lang.Thread.run(Thread.java:818)

#9. Crashlytics Exception Handler1
at dalvik.system.VMStack.getThreadStackTrace(VMStack.java)
at java.lang.Thread.getStackTrace(Thread.java:580)
at java.lang.Thread.getAllStackTraces(Thread.java:522)
at com.crashlytics.android.core.CrashlyticsController.writeSessionEvent(CrashlyticsController.java:1114)
at com.crashlytics.android.core.CrashlyticsController.writeFatal(CrashlyticsController.java:852)
at com.crashlytics.android.core.CrashlyticsController.access$400(CrashlyticsController.java:59)
at com.crashlytics.android.core.CrashlyticsController$6.call(CrashlyticsController.java:292)
at com.crashlytics.android.core.CrashlyticsController$6.call(CrashlyticsController.java:285)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at io.fabric.sdk.android.services.common.ExecutorUtils$1$1.onRun(ExecutorUtils.java:75)
at io.fabric.sdk.android.services.common.BackgroundPriorityRunnable.run(BackgroundPriorityRunnable.java:30)
at java.lang.Thread.run(Thread.java:818)

#10. OkHttp ConnectionPool
at java.lang.Object.wait(Object.java)
at com.android.okhttp.ConnectionPool.performCleanup(ConnectionPool.java:319)
at com.android.okhttp.ConnectionPool.runCleanupUntilPoolIsEmpty(ConnectionPool.java:256)
at com.android.okhttp.ConnectionPool.access$000(ConnectionPool.java:59)
at com.android.okhttp.ConnectionPool$1.run(ConnectionPool.java:102)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#11. FinalizerWatchdogDaemon
at java.lang.Object.wait(Object.java)
at java.lang.Daemons$FinalizerWatchdogDaemon.waitForObject(Daemons.java:270)
at java.lang.Daemons$FinalizerWatchdogDaemon.run(Daemons.java:242)
at java.lang.Thread.run(Thread.java:818)

#12. AsyncTask #3
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:410)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#13. Queue
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.PriorityBlockingQueue.take(PriorityBlockingQueue.java:510)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.performOperation(DependencyPriorityBlockingQueue.java:197)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.get(DependencyPriorityBlockingQueue.java:236)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:65)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:46)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#14. UnityChoreographer
at android.os.MessageQueue.nativePollOnce(MessageQueue.java)
at android.os.MessageQueue.next(MessageQueue.java:323)
at android.os.Looper.loop(Looper.java:143)
at android.os.HandlerThread.run(HandlerThread.java:61)

#15. pool-5-thread-1
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2053)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1090)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:806)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#16. main
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198)
at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:418)
at java.util.concurrent.FutureTask.get(FutureTask.java:175)
at com.crashlytics.android.core.CrashlyticsBackgroundWorker.submitAndWait(CrashlyticsBackgroundWorker.java:41)
at com.crashlytics.android.core.CrashlyticsController.handleUncaughtException(CrashlyticsController.java:285)
at com.crashlytics.android.core.CrashlyticsController$5.onUncaughtException(CrashlyticsController.java:269)
at com.crashlytics.android.core.CrashlyticsUncaughtExceptionHandler.uncaughtException(CrashlyticsUncaughtExceptionHandler.java:30)
at com.unity3d.player.k.uncaughtException(Unknown Source)
at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:693)
at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:690)

#17. AsyncTask #2
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:410)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#18. Answers Events Handler1
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2053)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1090)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:806)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at io.fabric.sdk.android.services.common.ExecutorUtils$1$1.onRun(ExecutorUtils.java:75)
at io.fabric.sdk.android.services.common.BackgroundPriorityRunnable.run(BackgroundPriorityRunnable.java:30)
at java.lang.Thread.run(Thread.java:818)

#19. pool-6-thread-1
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1078)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:806)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#20. pool-4-thread-1
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2053)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1090)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:806)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#21. Queue
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.PriorityBlockingQueue.take(PriorityBlockingQueue.java:510)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.performOperation(DependencyPriorityBlockingQueue.java:197)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.get(DependencyPriorityBlockingQueue.java:236)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:65)
at io.fabric.sdk.android.services.concurrency.DependencyPriorityBlockingQueue.take(DependencyPriorityBlockingQueue.java:46)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#22. AsyncTask #1
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:410)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

#23. AsyncTask #5
at java.lang.Object.wait(Object.java)
at java.lang.Thread.parkFor$(Thread.java:1220)
at sun.misc.Unsafe.park(Unsafe.java:299)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2013)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:410)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1036)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1098)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)
`

I believe we found the issue, and have a fix for it in the next release. I don't have an exact date when the fix will be available, but it should be out soon.

Thanks @alexames , I'll be waiting for the next release

The Firebase Unity 5.2.0 SDK fixes this issue. Please let us know if you have any problems with it.