java.util.ConcurrentModificationException in activity onCreate

Question

In a recent release where I added MoPub via Admob ad mediation I am seeing a bunch of ConcurrentModificationException in crash logs. It all seems to be native code and I am

Answer 1

Revert your Firebase Core library to:

implementation 'com.google.firebase:firebase-core:17.1.0'

I've seen this crash on both v17.2.1 and v17.2.2, but since reverting to 17.1.0 all has been fine.

I've reported the bug here: https://firebase.google.com/support/troubleshooter/report/bugs

Update

Thanks @Sébastien, reverting to v17.2.0 should also work:

implementation 'com.google.firebase:firebase-core:17.2.0'

Answer 2

We've identified the issue, and are working on a fix for the next release of the SDK.

Answer 3

It is finally fixed in 17.2.3: https://firebase.google.com/support/release-notes/android#analytics_v17-2-3

Answer 4

We have recently encountered a similar problem. Error in the Unity Ads adapter for Admob mediation.

Here is our build.gradle file:

implementation 'com.google.android.gms:play-services-ads:19.1.0'
implementation 'com.google.ads.mediation:unity:3.4.2.1'
implementation 'com.google.ads.mediation:vungle:6.5.3.0'
implementation 'com.google.ads.mediation:chartboost:7.5.0.0'
implementation 'com.google.ads.mediation:mytarget:5.6.3.0'
implementation 'com.yandex.android:mobmetricalib:3.13.1'
implementation 'com.yandex.android:mobileads:2.142'
implementation 'com.yandex.ads.adapter:admob-mobileads:0.3.0'

implementation 'com.google.android.gms:play-services-games:19.0.0'
implementation 'com.google.android.gms:play-services-auth:17.0.0'

implementation 'com.google.firebase:firebase-analytics:17.3.0'
implementation 'com.google.firebase:firebase-dynamic-links:19.1.0'
implementation 'com.crashlytics.sdk.android:crashlytics:2.10.1'

implementation 'com.google.android.play:core:1.7.2'
implementation 'androidx.multidex:multidex:2.0.1'

Error in Google Play console:

java.util.ConcurrentModificationException: 
  at java.util.HashMap$HashIterator.nextNode (HashMap.java:1453)
  at java.util.HashMap$EntryIterator.next (HashMap.java:1487)
  at java.util.HashMap$EntryIterator.next (HashMap.java:1485)
  at com.google.ads.mediation.unity.UnitySingleton$UnitySingletonListener.onUnityAdsError (UnitySingleton.java:227)
  at com.unity3d.services.ads.configuration.AdsModuleConfiguration$3.run (AdsModuleConfiguration.java:92)
  at android.os.Handler.handleCallback (Handler.java:888)
  at android.os.Handler.dispatchMessage (Handler.java:100)
  at android.os.Looper.loop (Looper.java:213)
  at android.app.ActivityThread.main (ActivityThread.java:8178)
  at java.lang.reflect.Method.invoke (Native Method)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:513)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1101)

Is this problem related to firebase again?

UPDATE

It looks like the problem this time is in the UnityAds adapter: https://developers.google.com/admob/android/mediation/unity#version-3.4.2.2

Answer 5

In our case, we are only seeing the crash with

com.google.firebase:firebase-analytics:17.2.2 

reverting to 17.2.1 has fixed the problem

This happens too if you are using firebase-core:17.2.2, because firebase-analytics is the same library rebranded. Take into account that as per official docs, current usage of firebase-core is deprecated -> https://firebase.google.com/support/release-notes/android#latest_sdk_versions