Repository navigation
Different refresh behavior across Android and iOS on Metro 0.81.1 #1440
Description
Hey folks, on React Native 0.76.7, Metro version 0.81.1, I'm seeing different refresh behavior across Android and iOS on a clean React Native community CLI app. I'm not sure if this falls within the boundaries of a React native issue or a Metro issue. Starting here because the Metro server itself is the entrypoint into demonstrating the bug. I would be happy to file this elsewhere if it's not actually a Metro concern. Thanks for your consideration and time either way!
Here's a reproducer: https://github.com/coolsoftwaretyler/Metro-Refresh-Reproducer
Here's the most relevant code:
What I expect
If I tap "R" in Metro, I should see the useEffect cleanup function in my logs. Then metro restarts. Then I see the useEffect start message. I would not expect to ever see the AppState change. I would expect the same behavior from Fast Refresh if I update the App.tsx file, since that useEffect hook is in there, and is going to always update, based on my interpretation from the fast refresh docs.
I would expect this behavior to be the same on both Android and iOS.
What happens
On iOS, the behavior works exactly as I expect.
On Android, I see some intermittently different behavior.
When I tap "R" in Metro server: In some cases, I get the useEffect cleanup. In others, I never see it. Very often, I also see AppState report that the state has changed to background.
When I update App.tsx and get a fast refresh: I see the behavior I expect more consistently.
If I add //@refresh reset to the top of the file: no change, but I see the useEffect cleanup more frequently, along with a huge wall of state changes to background after setting it.
Video recording
From the reproducer: https://www.dropbox.com/scl/fi/0wfdxz2dnknb1hyik1rxd/Screen-Recording-2025-02-23-at-2.55.59-PM.mov?rlkey=5g7ml59jrmg4p5l0asrifjylj&st=hxwlcdyb&dl=0
Activity
RobertKohde commentedon Jun 20, 2025
Hi,
Are there any workarounds for this issue? It is becoming a real pain when developing, since I cannot set required properties, clear listeners or subscriptions when the app closes. Furthermore, it makes testing a lot more difficult.
coolsoftwaretyler commentedon Jun 20, 2025
@RobertKohde - I never found a good workaround for it, but I wrapped up the project where it was a big issue for me so I stopped poking around at it.
NorseGaud commentedon Jul 5, 2025
Is this related? react/react-native#52447
Backgrounding the metro connected app for more than 5 seconds seems to cause
Error occurred, shutting down websocket connection: Websocket exceptionand lose its connection to the appRobertKohde commentedon Jul 7, 2025
It might be related, but in my case the clean-up of the
useEffectdoes not fire or rarely fires on android. The app state listener seems to, at least, properly log the app state. In my case, I use this clean-up to close a UDP socket, should it exist. Since it does not fire, the app creates a new socket with new listeners.Like mentioned in the thread you posted, it does not seem to be an issue in production/release, but it is a hassle to develop with.
Note: The
useEffectI am talking about was created in the main app function insideapp.tsx