android.view.AbsSavedState$1 cannot be cast to android.widget.CompoundButton$SavedState

Question

I am seeing the following error on Crashlytics with a lot of incidences:

Caused by java.lang.ClassCastException: android.view.AbsSavedState$1 cannot be cast to android.widget.CompoundButton$SavedState
       at android.widget.CompoundButton.onRestoreInstanceState(CompoundButton.java)
       at android.view.View.dispatchRestoreInstanceState(View.java)
       at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java)
       at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java)
       at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java)
       at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java)
       at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java)
       at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java)
       at android.view.View.restoreHierarchyState(View.java)
       at android.support.v4.app.Fragment.restoreViewState(Fragment.java:494)
       at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1486)
       at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
       at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
       at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(FragmentManager.java:3269)
       at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:3229)
       at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:2466)
       at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1483)
       at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
       at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
       at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(FragmentManager.java:3269)
       at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:3229)
       at android.support.v4.app.FragmentController.dispatchActivityCreated(FragmentController.java:201)
       at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:620)
       at android.support.v7.app.AppCompatActivity.onStart(AppCompatActivity.java:178)
       at android.app.Instrumentation.callActivityOnStart(Instrumentation.java)
       at android.app.Activity.performStart(Activity.java)
       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java)
       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java)
       at android.app.ActivityThread.access$900(ActivityThread.java)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java)
       at android.os.Handler.dispatchMessage(Handler.java)
       at android.os.Looper.loop(Looper.java)
       at android.app.ActivityThread.main(ActivityThread.java)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)

However this stack trace says nothing about my codebase, since the exception is thrown at the platform level.

From what I read this might have to do with duplicate ids, but I cant find any in my code, any ideas on how to debug this?

I also tried to enable "Dont keep activities" on Developer options to force an instance restoration but I am unable to reproduce the crash manually.

Answer 1

this can be caused by a view with the same resId, as the containing layout's name (main cause).

it could also be caused from view with duplicate resIds, but that's less likely the cause.

reviewing all the fragment's XML suggested (difficult to tell which one causes that).

but Edit > Find > Find in Path ...makes it easy to search for occurrences;

to search for one layout's name after the other; then to search for view's resId.

Answer 2

Well turns out I am using the new Chip component (extending CompoundButton), and had one group with a chip without an id.

And this somehow causes the app to crash on older phones (Android 6) because of the same id being assigned to multiple chips I can only guess.

I removed that Chip (which was not necessary anyway) and it does not crash anymore.