IssueTracker

I'm still having the same issues in:
Android Studio 3.3 Canary 12
Build #AI-182.4505.22.33.5026711, built on September 24, 2018
JRE: 1.8.0_152-release-1248-b01 x86_64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
macOS 10.13.6

Any updates on this? Have you been able to reproduce it? It's a release blocker on our end — any resonable workaround would be appreciated.

I think I have an idea of what is going on. Do you see a Log.INFO message saying: "Ignoring popBackStack to destination __ as it was not found on the current back stack"? If so, that means we're doing exactly what you said - popping id/graph off the stack - but not actually what you want (the parent graph to continue to be around if you are navigating forward as well)

If so, one workaround is to use popUpTo="@+id/a" and popUpTo"@+id/b" for action x and y, respectively - if you know that x is always clearing A off the stack, then popUpTo B is enough.

Alright, interesting! So that means there is no generic way to say that "clear everything of the backstack before moving to this next destination"? Rather, you need to keep track of every individual case? What if, for example, you have to following graph:
    x         y       z
A --> B --> C --> D

Where
  - A could be a splash screen and the start destination of the graph
  - B could be some welcome screen, prompting the user to sign in
  - C could be the actual login screen where the user enters his/hers details and signs in
  - D could be the main content screen

Obviously the user should not be allowed to click the back button from B to go back to the splash screen, and neither should the user be allowed to click the back button from D to go back to the login screen. In both of these cases the user should instead exit the app. However, it's perfectly fine for the user to click back from C and go back to the welcome screen B.

Now, to the problem; with your suggested workaround we can indeed set popUpTo="@+id/a" on x, but if we set popUpTo="@+id/c" on z then the user can still click the back button, but they will go to B instead. The desired behaviour is for the user to exit the app when clicking back when in D. The workaround stops working as we don't pop the back stack when going from B --> C, as we want to allow the user to navigate back to B from C.