IssueTracker

Is this specific to navigation? Or can this be reproduced with another other Composable component?

It only happens inside of a NavHost. So, yes, it seems to be specific to navigation.

This was caused by the fix to b/182284739 which made BackHandler lifecycle aware. The problem here is that the NavController registers its lifecycle and added an observer to the Activity Lifecycle in composition while the BackHandler registers its observer on the Activity Lifecycle in a DisposbleEffect. This means that the NavController will always get Lifecycle callbacks before the BackHandler, so the components listening the the NavController's lifecycle (like the NavBackStackEntry) will always get their Lifecycle callbacks before the BackHandler as well.

This should be addressed by work coming in 2.7 to integrate the BackHandler into the NavHost.

This has been fixed internally and will be available in Navigation 2.7.0-beta01.

The following release(s) address this bug.It is possible this bug has only been partially addressed:

• androidx.navigation:navigation-compose:2.7.0-beta01

I wouldn't say this is fixed. If you add a back-callback in the activity which is lifecycle aware, and then background->foreground the app, the activity back-callback will be put on top of the callback pile. This leads to that any BackHandler in your composable will NOT be triggered.

The best workaround I have for now is to use the non-lifecycle aware function in the activity.

class MainActivity : FragmentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        // open fragment which hoists the composables
        ...

        if (savedInstanceState == null) {
             onBackPressedDispatcher.addCallback(onBackPressedCallback = someBackHandling())  
            // onBackPressedDispatcher.addCallback(owner = this, onBackPressedCallback = someBackHandling)  // not this one
        }
    }

https://developer.android.com/jetpack/androidx/releases/navigation#2.7.0-beta01 :

Bug Fixes : NavHost in Navigation Compose now correctly intercepts system back calls even after the Activity has been STOPPED and RESUMED.

It works fine for me.