Resolve Fast Refresh Issues
This page provides solutions to common issues you might encounter when using Fast Refresh. If you don't find a solution to your specific problem here, post an issue in Developer Forum for additional support.
Port 8081 already in use
Error:
error listen EADDRINUSE: address already in use :::8081
Cause: This happens when:
-
Another Metro bundler instance is running.
-
A previous Fast Refresh session wasn't properly terminated.
-
Another app is using port 8081.
Solution:
-
Find the process that uses port 8081:
lsof -i:8081
-
Kill the specific process or all processes on port 8081:
# Kill the specific process kill -9 <process ID (PID)> # For example kill -9 62619 # Kill all processes lsof -i:8081 | xargs kill -9
-
Restart Metro:
npm start
App not reflecting changes
Cause: Fast Refresh fails to show code changes when the wrong build variant is used for your device's architecture. Each device requires a specific debug build type to properly support Fast Refresh functionality.
Solution: Use the correct debug build variant for your device:
- Fire TV Device: Use
*_armv7.vpkg
- Mac Intel Vega Virtual Device: Use
*_x86_64.vpkg
- Mac M1/M2 Vega Virtual Device: Use
*_aarch64.vpkg
No connection to Metro Server
Cause: The Metro Server is unable to establish a connection with your device, which prevents Fast Refresh from functioning. This is indicated by a "Pending… Device connection" message in the Metro Server.
Solution:
- Verify if port forwarding is active.
- Check if your device serial number is correct.
- Make sure both terminals (Metro Server and app) are running.
- Confirm you're using port 8081 for the Metro Server connection.
Architecture mismatch
Cause: The app crashes or fails to launch due to a mismatch between the device architecture and the built app package (.vpkg
file). This occurs when the app is compiled for a different architecture than the one your device uses.
Solution:
- Check if your device architecture matches the .vpkg file.
- Use
kepler device info
command to verify the device architecture. - If there's a mismatch, rebuild your app with the correct architecture.
Related topics
Last updated: Sep 30, 2025