'kotlin.TypeCastException: null cannot be cast to non-null type androidx.navigation.fragment.NavHostFragment at NavigationExtensionsKt

Exception

I copied the NavigationExtensions.kt extension file from the NavigationAdvancedSample and I get this exception:

Solution 1:^[1]

UPDATE: make sure your menu item ids are the same as your navigation resource files ids

also: if you're having a problem with ItemReselectedListener Add null safety checks, your listener should be something like this:

setOnNavigationItemReselectedListener { item ->
        val newlySelectedItemTag = graphIdToTagMap[item.itemId]
        val selectedFragment = fragmentManager.findFragmentByTag(newlySelectedItemTag)
                as NavHostFragment?
        val navController = selectedFragment?.navController
        // Pop the back stack to the start destination of the current navController graph
        navController?.popBackStack(
            navController.graph.startDestination, false
        )
    }

Solution 2:^[2]

In my case, I forgot to add android:name="androidx.navigation.fragment.NavHostFragment" in FragmentContainerView

Solution 3:^[3]

I also faced this probelem, the solution is actually very simple.

Make sure your menu item's id match the id of NAV_GRAPH not destinations.

I was using the same ids for menu items and destinations, but in this case, menu item should have same id as of NAV_GRAPH.

Solution 4:^[4]

I also had the same issue

Check that you have set your start destination and attached it to a fragment. in your nav graph set app:startDestination="@id/your fragment"

this should solve your problem

Solution 5:^[5]

I manage to solve this problem.

In my case, I was calling val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment before setContentView(binding.root) so I change the order of the methods and everything was Ok.

Solution 6:^[6]

can you try with this?

val selectedFragment: NavHostFragment? = fragmentManager.findFragmentByTag(newlySelectedItemTag) as NavHostFragment

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1
Solution 2	Harshal Pudale
Solution 3
Solution 4	Andrew Ananda
Solution 5	Desilio do Carmo Lima Neto
Solution 6	Dimitar

'kotlin.TypeCastException: null cannot be cast to non-null type androidx.navigation.fragment.NavHostFragment at NavigationExtensionsKt

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]

Solution 6:[6]