Android: NoClassDefFoundError android.os.AsyncTask

Yes, looks like it is a problem with one of the versions of Google play Services. See https://code.google.com/p/android/issues/detail?id=81083

A work around is to add:

try {      Class.forName("android.os.AsyncTask");}catch(Throwable ignore) {      // ignored}

into your Application#onCreate()

this appears to ensure that the root classloader loads AsyncTask so that it is then available from within Play Services.

It looks like yet another Google Play Services bug...

https://groups.google.com/forum/#!topic/google-admob-ads-sdk/_x12qmjWI7M

Edit: confirmed by Google staff => https://groups.google.com/d/msg/google-admob-ads-sdk/_x12qmjWI7M/9ZQs-v0ZZTMJ

Same issue here. I see them for 95% of the cases on android 4.0.3 devices. remaining 5% for 2.3 devices

Errors are randomly occurring from different parts of the code. Some examples:

   java.lang.NoClassDefFoundError: android/os/AsyncTask   at android.webkit.WebView.setupPackageListener(WebView.java:1305)   at android.webkit.WebView.<init>(WebView.java:1176)   at android.webkit.WebView.<init>(WebView.java:1136)

and

   java.lang.NoClassDefFoundError: android/os/AsyncTask   at android.webkit.WebView.setupPackageListener(WebView.java:1354)   at android.webkit.WebView.access$10900(WebView.java:363)   at android.webkit.WebView$PrivateHandler.handleMessage(WebView.java:10411)

and

   java.lang.NoClassDefFoundError: android.os.AsyncTask   at android.webkit.WebView.setupPackageListener(WebView.java:1385)   at android.webkit.WebView.<init>(WebView.java:1192)   at android.webkit.WebView.<init>(WebView.java:1150)   at android.webkit.WebView.<init>(WebView.java:1135)   at android.webkit.WebView.<init>(WebView.java:1106)   at android.webkit.WebView.<init>(WebView.java:1093)   at com.google.android.gms.ads.internal.util.g.f(SourceFile:400)   at com.google.android.gms.ads.internal.util.g.a(SourceFile:385)

it is completely unclear why these errors are happening. usually i dont see anything in the stacktrace pointing to my code.