Attempted to assign to readonly property

[marcshilling]

Getting a crash report from a React Native app that's crashing in react code. I can't really provide much detail other than the stack trace. All I know is it's our most frequent crash by far (73% of crashes are this one). Has anyone else run into this?

*** Terminating app due to uncaught exception 'RCTFatalException: Unhandled JS Exception: Attempted to assign to readonly property.', reason: 'Unhandled JS Exception: Attempted to assign to readonly property., stack:
m@17:659
recordTouchTrack@17:1373
extractEvents@16:30232
extractEvents@16:8354
handleTopLevel@17:4047
_receiveRootNodeIDEvent@17:3437
receiveTouches@17:3819
value@12:23605
<unknown>@12:21824
_@12:20918
value@12:21796

[jimfb]

Sounds like this is intended for the react native repository at https://github.com/facebook/react-native, I'm going to close this out in favor of posting there.

[marcshilling]

I found the bug...it's in the react core code base...soooo I'm pretty sure I'm in the right place here.

[jimfb]

... can you elaborate? How do we reproduce this in the core?

[marcshilling]

#6278

@jimfb I'm not sure how to reproduce this in core because I believe it's specific to how React Native uses it. I've referenced the React Native issue that discusses this crash.

[jimfb]

Yeah, I agree. That's why I initially suggested posting in the react-native repository. Doing something like #6278 would just hide the problem, making it more difficult to debug/reproduce/witness. And even with the #6278 "fix", you would be loosing events, which is a bad user experience. I'm going to close this out in favor of facebook/react-native#5246, because I don't think there is anything actionable here. If the RN team bounces it back here, we can re-investigate.

[everfire130]

I see the same crash in my release app.RN0.23.0. iOS most in 9.3.1 . Has the issue been fixed in 0.24？

[marcshilling]

@everfire130 it's fixed in 0.24. Scroll down to iOS bug fixes to see the detailed commits..."Fix how native events are coalesced when sending them to JS, specifically touch and scroll events, in order to respect their ordering"