Android 13: Crash in WindowOnBackInvokedDispatcher / OnBackPressedDispatcher [291869278]

Fixed

Bug

androidx-activity-1.8.0-alpha07

Status Update

No update yet.

Description

be...@airbnb.com

created issue #1

Jul 19, 2023 06:45PM

Since enabling android 13's enableOnBackInvokedCallback setting, our app has been experiencing a number of sporadic crashes originating in android only code.

Our app only uses OnBackPressedCallback, and registers using LifecycleOwners. (We do not change OnBackInvokedDispatcher).

java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Handler android.app.FragmentHostCallback.getHandler()' on a null object reference
        at android.app.FragmentManagerImpl.ensureExecReady(FragmentManager.java:2008)
        at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2061)
        at android.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:874)
        at android.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:835)
        at android.app.Activity.onBackPressed(Activity.java:4083)
        at androidx.activity.ComponentActivity.access$001(ComponentActivity.java:121)
        at androidx.activity.ComponentActivity$1.run(ComponentActivity.java:165)
        at androidx.activity.OnBackPressedDispatcher.onBackPressed(OnBackPressedDispatcher.kt:216)
        at androidx.activity.OnBackPressedDispatcher$2.invoke(OnBackPressedDispatcher.kt:102)
        at androidx.activity.OnBackPressedDispatcher$2.invoke(OnBackPressedDispatcher.kt:102)
        at androidx.activity.OnBackPressedDispatcher$Api33Impl.createOnBackInvokedCallback$lambda$0(OnBackPressedDispatcher:286)
        at androidx.activity.OnBackPressedDispatcher$Api33Impl$$InternalSyntheticLambda$1$5dea06066ea46437e84a2264f31c2ea84a3652ee19c7688a4a1451cf132e3013$0.onBackInvoked(OnBackPressedDispatcher:3)
        at android.window.WindowOnBackInvokedDispatcher$OnBackInvokedCallbackWrapper.lambda$onBackInvoked$3$android-window-WindowOnBackInvokedDispatcher$OnBackInvokedCallbackWrapper(WindowOnBackInvokedDispatcher.java:287)
        at android.window.WindowOnBackInvokedDispatcher$OnBackInvokedCallbackWrapper$$ExternalSyntheticLambda0.run(Unknown:2)
        at android.os.Handler.handleCallback(Handler.java:942)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loopOnce(Looper.java:226)
        at android.os.Looper.loop(Looper.java:313)
        at android.app.ActivityThread.main(ActivityThread.java:8757)
        at java.lang.reflect.Method.invoke(Method.java:-2)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1067)

I have not been able to create a reliable reproduction, however, have a hypothesis from reading through the source code.

The nature of the crash invoking the fallbackHandler implies that WindowOnBackInvokedDispatcher is invoking an OnBackPressedDispatcher with no enabled OnBackPressedCallbacks. The crash itself seems to imply the FragmentManager has been destroyed.
This appears somewhat unexpected from the platform, as in OnBackPressedDispatcher, there is logic to ensure when there are no active callbacks the window dispatcher is updated to not have the OnBackPressedDispatcher as the "topCallback". Instead the Activity's navigateBack is used. Notably, navigateBack does not perform a popBackStackImmediate which is different from the OnBackPressedDispatchers fallback which ultimately invokes onBackPress and popBackStackImmediate
The WindowOnBackInvokedDispatcher uses a weak reference to the proper back callback which is created via setTopOnBackInvokedCallback.
Since back presses are enqueued on a handler in WindowOnBackInvokedDispatcher, if there is a back-press enqueued while there is another message ahead of it which will cause WindowOnBackInvokedDispatcher to update it's topCallback, it can run on a stale callback.

This race condition ultimately means that Activity.onBackPressed is invoked instead of Activity.navigateBack, exposing the app to the crash in fragment manager's popBackStackImmediate.

This is just speculation, but from our crash breadcrumbs it does seem that this crash is also proceeded by the destroy event of an activity 5-100ms prior.

It would be much appreciated to have the perspective of someone more familiar with the platform code. We are seeing a steady increase in this crash as more users adopt android 13.

Comments

su...@google.com <su...@google.com> Jul 20, 2023 07:37AM

Assigned to su...@google.com.

su...@google.com <su...@google.com> #2Jul 20, 2023 09:02AM

We have some support in androidx.compose.ui.autofill

Leaving this bug open in case Ralston wants to add more info

kj...@gmail.com <kj...@gmail.com> #3Jul 20, 2023 06:59PM

I found an example here. One problem is that it only works with the Google autofill service. When using any other service like Microsoft Authenticator or OneKey, the following error is shown:

D/Autofill Status: Autofill popup isn't shown because autofill is not available.
    
    Did you set up autofill?
    1. Go to Settings > System > Languages&input > Advanced > Autofill Service
    2. Pick a service
    
    Did you add an account?
    1. Go to Settings > System > Languages&input > Advanced
    2. Click on the settings icon next to the Autofill Service
    3. Add your account

Is this a bug on your side or do the app developers of these password managers need to change their implementation?

lo...@gmail.com <lo...@gmail.com> #4Jul 23, 2023 07:16PM

Another problem I am facing with autofill is that it won't save my credentials. I tried forcing to finish the context as described here, but it won't do that either although I filled in the username with the one provided by the Google autofill service.

be...@airbnb.com <be...@airbnb.com> #5Jul 24, 2023 04:46PM

deleted

fe...@gmail.com <fe...@gmail.com> #6Jul 26, 2023 05:08PM

Facing the same issue here, Google autofill service seems to work. Zero documentation on adding support for Autofill framework on jetpack compose.

su...@google.com <su...@google.com> Aug 3, 2023 02:34PM

Status: New

il...@google.com <il...@google.com> #7Aug 4, 2023 10:00PM

Assigned to sa...@google.com.

Hello, I am trying to implement the same thing - it seems like there's no way for current password managers like 1Password or Bitwarden, to automatically pick up the fields. Is there a possible solution?

il...@google.com <il...@google.com> Aug 16, 2023 11:23PM

Reassigned to jb...@google.com.

ap...@google.com <ap...@google.com> #8Aug 17, 2023 12:49AM

I setup this modifier:

@OptIn(ExperimentalComposeUiApi::class)
fun Modifier.autofill(
    autofillTypes: List<AutofillType>,
    onFill: ((String) -> Unit),
) = composed {
    val autofill = LocalAutofill.current
    val autofillNode = AutofillNode(onFill = onFill, autofillTypes = autofillTypes)
    LocalAutofillTree.current += autofillNode

    this.onGloballyPositioned {
        autofillNode.boundingBox = it.boundsInWindow()
    }.onFocusChanged { focusState ->
        autofill?.run {
            if (focusState.isFocused) {
                requestAutofillForNode(autofillNode)
            } else {
                cancelAutofillForNode(autofillNode)
            }
        }
    }
}

And use it like this:

val emailState = remember { EmailState() }
Email(
    modifier = Modifier.autofill(
        autofillTypes = listOf(
            AutofillType.Username,
            AutofillType.EmailAddress
        ),
        onFill = { emailState.text = it },
    ),
    emailState = emailState,
    onImeAction = { onForgotPasswordSubmitted(emailState.text) }
)

With these steps, autofill works for me.

jb...@google.com <jb...@google.com> #9Aug 17, 2023 12:57AM

Marked as fixed.

@lo...@gmail.com comment#8

what version of compose are you using? I'm using latest alpha and the above doesn't work for me. 😭