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"React Native version mismatch" errors

When developing an Expo or React Native app, it's not uncommon to run into an error that looks like:
React Native version mismatch.

Javascript version: X.XX.X
Native version: X.XX.X

Make sure you have rebuilt the native code...

What this error means

The packager that you're running in your terminal (either with expo start or react-native start) is using a different version of react-native than the app on your device or emulator. This can happen after upgrading your React Native or Expo SDK version, or when connecting to the wrong local packager instance.

  • Close out any packagers you have running (you can list all terminal processes with the ps command, and search for Expo CLI or React Native CLI processes with ps -A | grep "expo\|react-native").
  • If this is a managed workflow project, either remove the sdkVersion field from your app.json file, or make sure it matches the value of the expo dependency in your package.json file.
  • If this is a managed workflow project, you should make sure your react-native version is correct. Run expo upgrade and follow the prompts. Expo CLI will make sure that your dependency versions for packages like expo and react-native are aligned. Your react-native version should be pointing to a .tar.gz file that has your SDK version in it, something like https://github.com/expo/react-native/archive/sdk-XX.X.X.tar.gz.
  • If this is a bare workflow project, and this error is occurring right after upgrading your React Native version, you should double-check that you've performed each of the upgrade steps correctly.
  • Finally:
    • Clear your bundler caches by running rm -rf node_modules && npm cache clean --force && npm install && watchman watch-del-all && rm -rf $TMPDIR/haste-map-* && rm -rf $TMPDIR/metro-cache && expo start --clear
      • Commands if you are using npm can be found here.
      • Commands if you are using Windows can be found here.
    • If this is a bare workflow project, run npx pod-install, then rebuild your native projects (run yarn android to rebuild for Android, and yarn ios to rebuild iOS)