Internal error caused by java.util.NoSuchElementException

[dimipaun]

We keep seeing this error in Crashlytics:

Fatal Exception: java.lang.RuntimeException: Uncaught exception in Firebase Database runloop (19.2.0). If you are not already on the latest version of the Firebase SDKs, try updating your dependencies. Should this problem persist, please file a report at https://github.com/firebase/firebase-android-sdk
       at com.google.firebase.database.android.AndroidPlatform$1$1.run(AndroidPlatform.java)
       at android.os.Handler.handleCallback + 751(Handler.java:751)
       at android.os.Handler.dispatchMessage + 95(Handler.java:95)
       at android.os.Looper.loop + 154(Looper.java:154)
       at android.app.ActivityThread.main + 6119(ActivityThread.java:6119)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run + 886(ZygoteInit.java:886)
       at com.android.internal.os.ZygoteInit.main + 776(ZygoteInit.java:776)

Caused by java.lang.RuntimeException: java.util.NoSuchElementException
       at com.google.firebase.database.core.persistence.DefaultPersistenceManager.runInTransaction(DefaultPersistenceManager.java)
       at com.google.firebase.database.core.SyncTree.removeEventRegistration(SyncTree.java)
       at com.google.firebase.database.core.SyncTree.removeAllEventRegistrations(SyncTree.java)
       at com.google.firebase.database.core.SyncTree$ListenContainer.onListenComplete(SyncTree.java)
       at com.google.firebase.database.core.Repo$4$1.onRequestResult(Repo.java)
       at com.google.firebase.database.connection.PersistentConnectionImpl.onListenRevoked(PersistentConnectionImpl.java)
       at com.google.firebase.database.connection.PersistentConnectionImpl.onDataPush(PersistentConnectionImpl.java)
       at com.google.firebase.database.connection.PersistentConnectionImpl.onDataMessage(PersistentConnectionImpl.java)
       at com.google.firebase.database.connection.Connection.onDataMessage(Connection.java)
       at com.google.firebase.database.connection.Connection.onMessage(Connection.java)
       at com.google.firebase.database.connection.WebsocketConnection.appendFrame(WebsocketConnection.java)
       at com.google.firebase.database.connection.WebsocketConnection.handleIncomingFrame(WebsocketConnection.java)
       at com.google.firebase.database.connection.WebsocketConnection.access$500(WebsocketConnection.java)
       at com.google.firebase.database.connection.WebsocketConnection$WSClientTubesock$2.run(WebsocketConnection.java)
       at java.util.concurrent.Executors$RunnableAdapter.call + 428(Executors.java:428)
       at java.util.concurrent.FutureTask.run + 237(FutureTask.java:237)
       at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run + 272(ScheduledThreadPoolExecutor.java:272)
       at java.util.concurrent.ThreadPoolExecutor.runWorker + 1133(ThreadPoolExecutor.java:1133)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run + 607(ThreadPoolExecutor.java:607)
       at java.lang.Thread.run + 761(Thread.java:761)

Caused by java.util.NoSuchElementException
       at java.util.AbstractList$Itr.next + 364(AbstractList.java:364)
       at java.util.AbstractList.hashCode + 540(AbstractList.java:540)
       at com.google.firebase.database.core.ValueEventRegistration.hashCode(ValueEventRegistration.java)
       at sun.misc.Hashing.singleWordWangJenkinsHash + 48(Hashing.java:48)
       at java.util.HashMap.getEntry + 393(HashMap.java:393)
       at java.util.HashMap.get + 348(HashMap.java:348)
       at com.google.firebase.database.core.ZombieEventManager.unRecordEventRegistration(ZombieEventManager.java)
       at com.google.firebase.database.core.ZombieEventManager.onZombied(ZombieEventManager.java)
       at com.google.firebase.database.core.EventRegistration.zombify(EventRegistration.java)
       at com.google.firebase.database.core.view.View.removeEventRegistration(View.java)
       at com.google.firebase.database.core.SyncPoint.removeEventRegistration(SyncPoint.java)
       at com.google.firebase.database.core.SyncTree$12.call(SyncTree.java)
       at com.google.firebase.database.core.SyncTree$12.call(SyncTree.java)
       at com.google.firebase.database.core.persistence.DefaultPersistenceManager.runInTransaction(DefaultPersistenceManager.java)
       at com.google.firebase.database.core.SyncTree.removeEventRegistration(SyncTree.java)
       at com.google.firebase.database.core.SyncTree.removeAllEventRegistrations(SyncTree.java)
       at com.google.firebase.database.core.SyncTree$ListenContainer.onListenComplete(SyncTree.java)
       at com.google.firebase.database.core.Repo$4$1.onRequestResult(Repo.java)
       at com.google.firebase.database.connection.PersistentConnectionImpl.onListenRevoked(PersistentConnectionImpl.java)
       at com.google.firebase.database.connection.PersistentConnectionImpl.onDataPush(PersistentConnectionImpl.java)
       at com.google.firebase.database.connection.PersistentConnectionImpl.onDataMessage(PersistentConnectionImpl.java)
       at com.google.firebase.database.connection.Connection.onDataMessage(Connection.java)
       at com.google.firebase.database.connection.Connection.onMessage(Connection.java)
       at com.google.firebase.database.connection.WebsocketConnection.appendFrame(WebsocketConnection.java)
       at com.google.firebase.database.connection.WebsocketConnection.handleIncomingFrame(WebsocketConnection.java)
       at com.google.firebase.database.connection.WebsocketConnection.access$500(WebsocketConnection.java)
       at com.google.firebase.database.connection.WebsocketConnection$WSClientTubesock$2.run(WebsocketConnection.java)
       at java.util.concurrent.Executors$RunnableAdapter.call + 428(Executors.java:428)
       at java.util.concurrent.FutureTask.run + 237(FutureTask.java:237)
       at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run + 272(ScheduledThreadPoolExecutor.java:272)
       at java.util.concurrent.ThreadPoolExecutor.runWorker + 1133(ThreadPoolExecutor.java:1133)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run + 607(ThreadPoolExecutor.java:607)
       at java.lang.Thread.run + 761(Thread.java:761)

[google-oss-bot]

I found a few problems with this issue:

• I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.
• This issue does not seem to follow the issue template. Make sure you provide all the required information.

[aguatno]

Hi @dimipaun Thanks for filing this issue. The error logs is similar to issue#890.

To check whether if this is a implementation issue, could you try to remove all third-party APIs and follow this Quickstart guide and see if you'll still encounter the issue?

[google-oss-bot]

Hey @dimipaun. We need more information to resolve this issue but there hasn't been an update in 7 days. I'm marking the issue as stale and if there are no new updates in the next 3 days I will close it automatically.

If you have more information that will help us get to the bottom of this, just add a comment!

[dimipaun]

Hi @aguatno ,

I don't think this is similar to #890 -- there the default Firebase App was deleted and a new one was created, thus causing the issue.

No such thing in this case -- we just use the default app.

Plus, this issue happens sporadically in production only, so there's no way to "remove all third-party libraries" as that would mean there would be no app left to deploy!

What I did notice is that it happens on particular devices:

• Motorola / Nexus 6 running Android 7.1.1 (72% of crashes)
• Samsung / Galaxy J7 running Android 9 (14% of crashes)
• Samsung / Galaxy S9+ running Android 9 (7% of crashes)
• Huawai / P20 lite running Android 9 (7% of crashes)

The funny bit is that the Galaxy S9+ and the Nexus 6 we use internally for testing so we know that most of the time it is working fine.

It doesn't seem related to the underlying OS, seems to be a bug in the libs themselves.

[aguatno]

Thanks for the information. Can you also share your dependencies from the build.gradle file?

[google-oss-bot]

Hey @dimipaun. We need more information to resolve this issue but there hasn't been an update in 7 days. I'm marking the issue as stale and if there are no new updates in the next 3 days I will close it automatically.

If you have more information that will help us get to the bottom of this, just add a comment!

[google-oss-bot]

Since there haven't been any recent updates here, I am going to close this issue.

@dimipaun if you're still experiencing this problem and want to continue the discussion just leave a comment here and we are happy to re-open this.