Component used: Fragment Version used: 1.3.0 Devices/Android versions reproduced on: Android 10, 11

This is happen on our product code, but, sorry, I could not create sample project to reproduce this issue.

If we update fragment from 1.2.5 to 1.3.0, onResume is not called on one Fragment of our project. This is very similer to https://issuetracker.google.com/issues/177154873

Our Fragment has custom enter/exit transition. If we remove these custom transition, onResume is called as expected. But we can't do that. We need custom transition animation. The difference to above issue (177154873) may that our Fragment is "Fragment on Fragment".

We tried to call FragmentManager.enableNewStateManager(false) written in
https://medium.com/androiddevelopers/fragments-rebuilding-the-internals-61913f8bf48e to disable new state manager.

onResume becomes to be called !! BUT, it cause ConcurrentModificationException.

java.util.HashMap$HashIterator.nextNode (HashMap.java:1441)
java.util.HashMap$KeyIterator.next (HashMap.java:1465)
androidx.fragment.app.FragmentManager.endAnimatingAwayFragments (FragmentManager.java:2489)
androidx.fragment.app.FragmentManager.dispatchDestroy (FragmentManager.java:3090)
androidx.fragment.app.Fragment.performDestroy (Fragment.java:3201)
androidx.fragment.app.FragmentStateManager.destroy (FragmentStateManager.java:771)
androidx.fragment.app.FragmentManager.moveToState (FragmentManager.java:1449)
androidx.fragment.app.FragmentManager.moveToState (FragmentManager.java:1509)
androidx.fragment.app.FragmentManager.moveFragmentToExpectedState (FragmentManager.java:1587)
androidx.fragment.app.FragmentManager.moveToState (FragmentManager.java:1649)
androidx.fragment.app.FragmentManager.executeOpsTogether (FragmentManager.java:2209)
androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute (FragmentManager.java:2094)
androidx.fragment.app.FragmentManager.execPendingActions (FragmentManager.java:1990)
androidx.fragment.app.FragmentManager$5.run (FragmentManager.java:524)
android.os.Handler.handleCallback (Handler.java:938)
android.os.Handler.dispatchMessage (Handler.java:99)
android.os.Looper.loop (Looper.java:223)
android.app.ActivityThread.main (ActivityThread.java:7660)
java.lang.reflect.Method.invoke (Method.java)
com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:592)
com.android.internal.os.ZygoteInit.main (ZygoteInit.java:947)

This is similar to following issues. https://issuetracker.google.com/issues/178460675 https://issuetracker.google.com/issues/152337205

But this is happen on 1.3.0.

Summary:

With new state manager : onResume is not called.
Without new state manager : ConcurrentModificationException is happen