Component used: navigation-fragment
Version used: 1.0.0-alpha05
Devices/Android versions reproduced on: Pixel 2 (Pie) / Emulator Nougat / Pie

I Stumbled on this stacktrace in a project that use the new navigation component:

java.lang.NumberFormatException: For input string: "TRANSACTION_NAME"
at java.lang.Integer.parseInt(Integer.java:615)
at java.lang.Integer.valueOf(Integer.java:801)
at androidx.navigation.fragment.FragmentNavigator.isBackStackEqual(FragmentNavigator.java:252)
at androidx.navigation.fragment.FragmentNavigator$1.onBackStackChanged(FragmentNavigator.java:83)
at androidx.fragment.app.FragmentManagerImpl.reportBackStackChanged(FragmentManager.java:2733)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2439)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2372)
at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:884)
at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:827)
at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:874)
at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:827)
at androidx.fragment.app.FragmentActivity.onBackPressed(FragmentActivity.java:190)
at android.app.Activity.onKeyUp(Activity.java:3082)

In one of my fragment I manage an internal fragment transaction

requireFragmentManager().beginTransaction()
.addToBackStack("TRANSACTION_NAME")
.commit()

from the fragment doing this I navigate to another using the nav graph and when i press back that stack trace pop up and the app crashes.

If i use navController.navigateUp() nothing happens.

Looking in the code of FragmentNavigator I see

Integer.valueOf(mFragmentManager
.getBackStackEntryAt(fragmentBackStackIndex--)
.getName())

apparently you assume any back stack entry name is an integer.

Is this a design decision? Does that means I can't use fragment transactions on my own if I use the navigation component?

I honestly only use this to detect the user pressing back in my fragment without having to rely on the activity forwarding the information cause I have an overlay view on top of my fragment that is supposed to go away when the user press back and I don't have an `onBackPressed()` on the fragment.