Can't popBackStack() after screen rotation. Android Navigation Components

Question

I'm using NavController: Navigation.findNavController(activity, R.id.statistic_host_fragment). And is everything good, until i rotate my device and after that i can't navigate() and popBackStack().

In logs: FragmentNavigator: Ignoring popBackStack() call: FragmentManager has already saved its state AND FragmentNavigator: Ignoring navigate() call: FragmentManager has already saved its state

When I saw Google Sample they didn't anything about this problem, there is all working fine. So I can't understand that is the problem.

Also when I'm using MVVM, I'm saving navController in viewModel, and after onCreate() reinit controller in viewModel. It solved navigate() problem after rotation but I still can't popBackStack(). After that I trying use Navigation.setViewNavController() but it not work.

val destId = currentController.currentDestination?.id

    if (destId != R.id.wikiFragment && destId != R.id.statisticsFragment && destId != R.id.trackerFragment)
        currentController.navigateUp()

and in HomeActivity:

override fun onBackPressed() {
    if (vm.currentController.graph.startDestination == vm.currentController.currentDestination?.id) {
        super.onBackPressed()
    } else {
        vm.currentController.popBackStack()
    }
}

and all source : https://github.com/SuperCatDev/OverHub/tree/feature/maps

Answer 1

Solved the problem by extracting all NavControllers from ViewModel and never keep NavController instance. Only use getter methods when acces needed.