Crash on Android 4.0.3 when preparing for InterstitialAd

[LionbI4]

Everything works well on all android devices except Android 4.0.3

The following code is crashing Unity3d application:

ad = new InterstitialAd("ca-app-pub-xxxxxxxxxxxxxxxx/xxxxxxxxxx");
AdRequest.Builder adBuilder = new AdRequest.Builder();
adBuilder.AddKeyword("game");
ad.LoadAd(adBuilder.Build());

Exception:

E/AndroidRuntime( 4175): FATAL EXCEPTION: main
E/AndroidRuntime( 4175): java.lang.Error: FATAL EXCEPTION [main]
E/AndroidRuntime( 4175): Unity version : 4.5.5f1
E/AndroidRuntime( 4175): Device model : samsung GT-P5100
E/AndroidRuntime( 4175): Device fingerprint: samsung/espresso10rfxx/espresso10rf:4.0.3/IML74K/P5100XWALD7:user/release-keys
E/AndroidRuntime( 4175):
E/AndroidRuntime( 4175): Caused by: java.lang.NoClassDefFoundError: android/os/AsyncTask
E/AndroidRuntime( 4175): at android.webkit.WebView.setupPackageListener(WebView.java:1637)
E/AndroidRuntime( 4175): at android.webkit.WebView.(WebView.java:1381)
E/AndroidRuntime( 4175): at android.webkit.WebView.(WebView.java:1342)
E/AndroidRuntime( 4175): at android.webkit.WebView.(WebView.java:1331)
E/AndroidRuntime( 4175): at android.webkit.WebView.(WebView.java:1299)
E/AndroidRuntime( 4175): at android.webkit.WebView.(WebView.java:1290)
E/AndroidRuntime( 4175): at com.google.android.gms.ads.internal.util.g.f(SourceFile:400)
E/AndroidRuntime( 4175): at com.google.android.gms.ads.internal.util.g.a(SourceFile:385)
E/AndroidRuntime( 4175): at com.google.android.gms.ads.internal.n.e.a(SourceFile:275)
E/AndroidRuntime( 4175): at com.google.android.gms.ads.internal.b.(SourceFile:290)
E/AndroidRuntime( 4175): at com.google.android.gms.ads.internal.b.(SourceFile:276)
E/AndroidRuntime( 4175): at com.google.android.gms.ads.AdManagerCreatorImpl.a(SourceFile:36)
E/AndroidRuntime( 4175): at com.google.android.gms.ads.internal.client.o.onTransact(SourceFile:66)
E/AndroidRuntime( 4175): at android.os.Binder.transact(Binder.java:297)
E/AndroidRuntime( 4175): at com.google.android.gms.internal.be$a$a.a(Unknown Source)
E/AndroidRuntime( 4175): at com.google.android.gms.internal.au.b(Unknown Source)
E/AndroidRuntime( 4175): at com.google.android.gms.internal.au.a(Unknown Source)
E/AndroidRuntime( 4175): at com.google.android.gms.internal.bi.v(Unknown Source)
E/AndroidRuntime( 4175): at com.google.android.gms.internal.bi.a(Unknown Source)
E/AndroidRuntime( 4175): at com.google.android.gms.ads.InterstitialAd.loadAd(Unknown Source)
E/AndroidRuntime( 4175): at com.google.unity.ads.Interstitial$2.run(Interstitial.java:95)
E/AndroidRuntime( 4175): at android.os.Handler.handleCallback(Handler.java:605)
E/AndroidRuntime( 4175): at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime( 4175): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime( 4175): at android.app.ActivityThread.main(ActivityThread.java:4514)
E/AndroidRuntime( 4175): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 4175): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime( 4175): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
E/AndroidRuntime( 4175): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
E/AndroidRuntime( 4175): at dalvik.system.NativeStart.main(Native Method)

[LionbI4]

Google play services version: 6111000
Using latest plugin from commit ab4078f

[ericleich]

I'm going to close this out since it isn't an issue of the Unity plugin itself. And I don't think it's an issue with the Mobile Ads SDK or even the core Android platform.

According to the Android docs, AsyncTask was introduced back in Android 1.5. So this class should definitely exist on Android 4.0.3, unless a special build of the device (in this case a special Samsung build) removed this class.

[LionbI4]

The thing is, when I build empty application with 1 scene and 1 simple script - everything works on the same device same android version. Full screen ad is showing fine.
It seems like it is conflicting with some other libraries: Facebook Sdk, Unibill or Google play services plugin. And I can't figure out which one.