JAVA

does not have a NavController set

val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
val navController = navHostFragment.navController

does not have a NavController set on 2131231008

// activity_main.xml
<fragment
       android:layout_width="match_parent"
       android:layout_height="match_parent"
        android:name="androidx.navigation.fragment.NavHostFragment"
       android:id="@+id/nav_host_fragment"
       app:navGraph="@navigation/mobile_navigation" />
         
// MainActivity.kt
val toolbar = findViewById<MaterialToolbar>(R.id.main_toolbar)
setSupportActionBar(toolbar)

does not have a NavController set

<androidx.fragment.app.FragmentContainerView
    android:id="@+id/nav_host_fragment"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="0dp"
    android:layout_height="0dp"
    app:defaultNavHost="true"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="parent"
    app:navGraph="@navigation/nav_graph"
    />