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:

1. Another Metro bundler instance is running.

2. A previous Fast Refresh session wasn't properly terminated.

3. Another app is using port 8081.

Solution:

1. Find the process that uses port 8081:

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   lsof -i:8081
   

2. Kill the specific process or all processes on port 8081:

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   # Kill the specific process
   kill -9 <process ID (PID)>
   
   # For example
   kill -9 62619
   
   # Kill all processes
   lsof -i:8081 | xargs kill -9
   

3. Restart Metro:

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   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:

1. Verify if port forwarding is active.
2. Check if your device serial number is correct.
3. Make sure both terminals (Metro Server and app) are running.
4. 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:

1. Check if your device architecture matches the .vpkg file.
2. Use kepler device info command to verify the device architecture.
3. If there's a mismatch, rebuild your app with the correct architecture.

Related topics

• Set Up Fast Refresh

Last updated: Sep 30, 2025