New Android App NullPointerException on first launch

[Sebastian Jug]

What is the issue?

I updated my Tailscale app on my Android device. I had my other VPN app running and set to the "Always-on VPN" in the settings.
I tried to launch the Tailscale app after updating. It would crash immediately.

Steps to reproduce

0. Have other VPN app running, connected, and set to always-on in settings.
1. Update Tailscale app to 1.66.3 via Google Play Store.
2. Launch Tailscale app (should try to start network automatically, if not start network manually).
3. Crash.

Are there any recent changes that introduced the issue?

The recent change was the app rewrite/uprade.

OS

Android

OS version

14

Tailscale version

1.66.3-teae73f821-g63a2bbc8e71

Other software

Other VPN app

Bug report

BUG-a820be88a1be0ad8b0f78a2ee14193dcd3fec85e0988dad38e3496f127afd610-20240515172921Z-fb47fd784292be6f

[Andrea Gottardo]

Can you please run adb logcat and provide us with the stack trace of the crash when it verifies? Thanks.

[Sebastian Jug]

Will do, I have this crash handy but it wasn't from adb logcat:

type: crash
osVersion: google/shiba/shiba:14/AP1A.240505.005/2024050700:user/release-keys
package: com.tailscale.ipn:219
process: com.tailscale.ipn
processUptime: 2610 + 378 ms
installer: com.android.vending

java.lang.NullPointerException: findFragmentByTag(...) must not be null
        at com.tailscale.ipn.App$Companion.startActivityForResult(App.kt:66)
        at com.tailscale.ipn.App.prepareVPN$lambda$1(App.kt:252)
        at com.tailscale.ipn.App.$r8$lambda$L4xZtibjmMdlYIKm1rrO1TWKG94(Unknown Source:0)
        at com.tailscale.ipn.App$$ExternalSyntheticLambda0.run(Unknown Source:6)
        at android.app.Activity.runOnUiThread(Activity.java:7838)
        at com.tailscale.ipn.App.prepareVPN(App.kt:245)
        at com.tailscale.ipn.MainActivity$onCreate$2$1.emit(MainActivity.kt:237)
        at com.tailscale.ipn.MainActivity$onCreate$2$1.emit(MainActivity.kt:235)
        at kotlinx.coroutines.flow.StateFlowImpl.collect(StateFlow.kt:392)
        at kotlinx.coroutines.flow.StateFlowImpl$collect$1.invokeSuspend(Unknown Source:15)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:104)
        at android.os.Handler.handleCallback(Handler.java:959)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loopOnce(Looper.java:232)
        at android.os.Looper.loop(Looper.java:317)
        at android.app.ActivityThread.main(ActivityThread.java:8532)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:552)
        at com.android.internal.os.ExecInit.main(ExecInit.java:50)
        at com.android.internal.os.RuntimeInit.nativeFinishInit(Native Method)
        at com.android.internal.os.RuntimeInit.main(RuntimeInit.java:359)
        Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@5ab2506, Dispatchers.Main.immediate]

It also crashes if I try to connect the app while the other VPN is connected & enabled as always-on.
Looks like the new app is not handling that condition.

edit: This is the same stack trace I'm seeing in logcat. Please let me know if you want that output instead.

[Andrea Gottardo]

Thanks! This really helps.

cc @kari-ts

[Naman Sood]

For those looking for a quick solution, clearing the app data and then re-logging in seemed to fix this for me.