NullPointerException - LifecycleRegistry.removeObserver

[sregg]

Description

We're getting a few NPE in our app in prod.

NullPointerException
Parameter specified as non-null is null: method androidx.lifecycle.LifecycleRegistry.removeObserver, parameter observer

Searching for removeObserver in our entire project returns only this line in react-native-screens:

react-native-screens/android/src/main/java/com/swmansion/rnscreens/LifecycleHelper.kt

Line 46 in 6272e44

mViewToLifecycleMap[view]?.removeObserver(view)

Steps to reproduce

We can't seem to reproduce.
It seems to be happening only on Android. Maybe on app start (we don't see any breadcrumbs in Sentry).

Snack or a link to a repository

Couldn't repro in snack.

Screens version

3.18.2

React Native version

0.71.8

Platforms

Android

JavaScript runtime

Hermes

Workflow

React Native (without Expo)

Architecture

Paper (Old Architecture)

Build type

Release mode

Device

Real device

Device model

Redmi Note 9 Pro Max - Android 11

Acknowledgements

Yes

[github-actions]

Hey! 👋

The issue doesn't seem to contain a minimal reproduction.

Could you provide a snack or a link to a GitHub repository under your username that reproduces the problem?

[sregg]

We can't even repro in our own app. It seems to be happening intermittently for some users only.

[AZIMAT]

I have this issue too,
We can't reproduce it. but some users were affected after updating compile SDK to 33.

[AZIMAT]

@sregg do you find any solutions?

[sregg]

I'm gonna do a patch using patch-package today and see if that fixes it.
I'll submit a PR if that helps.

[AZIMAT]

I'm gonna do a patch using patch-package today and see if that fixes it. I'll submit a PR if that helps.

fun <T> unregister(view: T) where T : View, T : LifecycleObserver? { if(view != null) { mViewToLifecycleMap[view]?.removeObserver(view) } }
I'm going to check this line of code.

[AZIMAT]

I'm gonna do a patch using patch-package today and see if that fixes it. I'll submit a PR if that helps.

May I have your patch?

[sregg]

I'm gonna do a patch using patch-package today and see if that fixes it. I'll submit a PR if that helps.

fun <T> unregister(view: T) where T : View, T : LifecycleObserver? { if(view != null) { mViewToLifecycleMap[view]?.removeObserver(view) } }
I'm going to check this line of code.

That was my plan for the patch

[AZIMAT]

I'm gonna do a patch using patch-package today and see if that fixes it. I'll submit a PR if that helps.

fun <T> unregister(view: T) where T : View, T : LifecycleObserver? { if(view != null) { mViewToLifecycleMap[view]?.removeObserver(view) } }
I'm going to check this line of code.

That was my plan for the patch

Please share your patch result.

[sregg]

Here's the patch:

diff --git a/node_modules/react-native-screens/android/src/main/java/com/swmansion/rnscreens/LifecycleHelper.kt b/node_modules/react-native-screens/android/src/main/java/com/swmansion/rnscreens/LifecycleHelper.kt
index 41bfc80..5925472 100644
--- a/node_modules/react-native-screens/android/src/main/java/com/swmansion/rnscreens/LifecycleHelper.kt
+++ b/node_modules/react-native-screens/android/src/main/java/com/swmansion/rnscreens/LifecycleHelper.kt
@@ -43,6 +43,9 @@ class LifecycleHelper {
     }
 
     fun <T> unregister(view: T) where T : View, T : LifecycleObserver? {
+        if (view == null) {
+            return
+        }
         mViewToLifecycleMap[view]?.removeObserver(view)
     }

[AZIMAT]

@sregg I have this issue in sentry again.

[sregg]

Even after that patch?

[AZIMAT]

Even after that patch?

Yeap.

[matous94]

I have the same problem, but my react-native-screen version (3.20.0) doesn't contain the file you patched anymore or any other removeObserver call. There are removeObserver calls in other dependencies though. Mostly expo libraries in my case. I tried to patch one suspicious file, that does some compatibility stuff between Expo and React Native Screens, but it didn't work.

https://github.com/expo/expo/blob/main/packages/expo-modules-core/android/src/main/java/expo/modules/kotlin/activityresult/AppContextActivityResultRegistry.kt

[AZIMAT]

@matous94 Can you reproduce this issue on a real device?

[matous94]

It actually happens only on real device, in preview/production build, which makes testing quite tedious, since it's not happening in Expo dev-client.

Also I just noticed the "Steps to reproduce" for this issue are different from mine. For me it happens when I call Updates.reloadAsync. I use it to reload app at logout, expired session token etc.

But I think it's quite possible that the underlying issue is the same/similiar.

[AZIMAT]

@sregg RNScreen 3.2 doesn't contain the file that we patched yesterday.

[sregg]

Does that mean it's fixed?
I'll try it out

[AZIMAT]

Does that mean it's fixed? I'll try it out

Nope, I published on production with version 3.2.0 and i have same issues in sentry.

[matous94]

I just got the following, more detailed error message in dev in terminal after hot-reloading. I will look into it later, but it seems the error might be coming from sentry package? Possibly the same issue

  androidx.lifecycle.LifecycleRegistry.removeObserver(Unknown Source:3)
  io.sentry.android.core.AppLifecycleIntegration.removeObserver(AppLifecycleIntegration.java:112)
  io.sentry.android.core.AppLifecycleIntegration.lambda$close$1$io-sentry-android-core-AppLifecycleIntegration(AppLifecycleIntegration.java:123)
  io.sentry.android.core.AppLifecycleIntegration$$ExternalSyntheticLambda0.run(Unknown Source:2)
  android.os.Handler.handleCallback(Handler.java:942)
  android.os.Handler.dispatchMessage(Handler.java:99)
  android.os.Looper.loopOnce(Looper.java:201)
  android.os.Looper.loop(Looper.java:288)
  android.app.ActivityThread.main(ActivityThread.java:7898)
  java.lang.reflect.Method.invoke(Native Method)
  com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
  com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)

[sregg]

Thanks @matous94
Looks promising: getsentry/sentry-java#2675.
Closing ticket.

[DiorAbjalilov]

I have this issue too, We can't reproduce it. but some users were affected after updating compile SDK to 33.

I also have sdk 33. how can I solve this problem