Expo Docs MCP Server

--- title: "React Native version mismatch" errors description: Learn about what React Native version mismatch means and how to resolve it in an Expo or React Native app. --- When developing an Expo or React Native app, it's common to run into an error that looks like: ## What this error means The bundler that you're running in your terminal (using `npx expo start`) is using a different JavaScript version of `react-native` than the native 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 development server. ## How to fix it - Close out any development servers that you have running (you can list all terminal processes with the `ps` command, and search for Expo CLI or React Native community CLI processes with `ps -A | grep "expo\|react-native"`). - If this is a Expo 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 Expo project, you should make sure your `react-native` version is correct. Run `npx expo-doctor` will show a warning where the `react-native` version you should install. If you did upgrade to a newer SDK, make sure to run `npx expo install --fix` and follow the prompts. Expo CLI will make sure that your dependency versions for packages like `expo` and `react-native` are aligned. - If this is a bare React Native project, and this error is occurring right after upgrading your React Native version, you should double-check that you have 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 && npx expo start --clear` - Commands if you are using npm can be found [here.](clear-cache-macos-linux) - Commands if you are using Windows can be found [here.](clear-cache-windows) - If this is a bare React Native project, run `npx pod-install`, then rebuild your native projects (run `yarn android` to rebuild for Android, and `yarn ios` to rebuild iOS)