Crash in Android: onInitializationComplete is called twice in MobileAds#initialize

Bug report

After we switched from firebase_admob to the google_mobile_ads Plugin (Version: 0.11.0+3) we are seeing repeating crashes of some of our Android users.

onInitializationComplete() of MobileAds#initialize in GoogleMobileAdsPlugin.java is called twice, which is not supported by DartMessenger.

Stack trace:

Fatal Exception: java.lang.IllegalStateException: Reply already submitted at io.flutter.embedding.engine.dart.DartMessenger$Reply.reply(DartMessenger.java:155) at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler$1.success(MethodChannel.java:238) at io.flutter.plugins.googlemobileads.GoogleMobileAdsPlugin$1.onInitializationComplete(GoogleMobileAdsPlugin.java:211) at com.google.android.gms.internal.ads.zzzn$zza.zze(zzzn.java:6) at com.google.android.gms.internal.ads.zzajn.zza(zzajn.java:11) at com.google.android.gms.internal.ads.zzgy.onTransact(zzgy.java:13) at android.os.Binder.transact(Binder.java:635) at gi.bd(gi.java:2) at com.google.android.gms.ads.internal.initialization.f.e(f.java) at com.google.android.gms.ads.nonagon.initialization.a.run(a.java:2) at android.os.Handler.handleCallback(Handler.java:790) at android.os.Handler.dispatchMessage(Handler.java:99) at qx.a(qx.java) at com.google.android.gms.ads.internal.util.zzaj.a(zzaj.java:1) at qx.dispatchMessage(qx.java) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:7000) at java.lang.reflect.Method.invoke(Method.java) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:441) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)

Steps to reproduce

We could not reproduce the crash by ourselves, yet, but we have several affected Android users.

Expected behavior

No crash, onInitializationComplete called once per app start

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Additional context

We use Google-Mobile-Ads as a mediation service and have included additional mediated ad networks:

• AppLovin
• Facebook
• IronSource
• UnityAds
• Vungle

For all affected users the first InitializationStatus result of MobileAds.instance.initialize() only contains informations about AdMob, the other expected ad networks are missing:

adapterStatuses: (com.google.android.gms.ads.MobileAds: AdapterStatus(state: AdapterInitializationState.ready, latency: 0.0))

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[kolotum]

Any updates on this? This is pretty critical issue - some user just can’t use app at all.

We have added a workaround in our fork: https://github.com/lotum/googleads-mobile-flutter/commit/868811eab40800b12e1a3da2afe1317ee6ff424f

We abort when onInitializationComplete is called again. So far we are not seeing any issues using this solution and the crash does not occur anymore with the above workaround.

[greymag]

Any updates on this? This is pretty critical issue - some user just can’t use app at all.