HomeGuidesReferenceLearn

Troubleshooting

Fixing common issues with Expo Router setup.


EXPO_ROUTER_APP_ROOT not defined

This applies to Expo Router v1 and the beta release.

If process.env.EXPO_ROUTER_APP_ROOT is not defined you'll see the following error:

Terminal
Invalid call at line 11: process.env.EXPO_ROUTER_APP_ROOT First argument of require.context should be a string.

This can happen when:

  • The project is using an expo version lower than expo@^46.0.13. Version 46.0.13 enables context modules and injects process.env.EXPO_ROUTER_APP_ROOT into the process.
  • The babel plugin expo-router/babel is not being used in the project babel.config.js. You can try clearing the cache with:
Terminal
npx expo start --clear

Alternatively, you can circumvent this issue by creating an index.js file in the root of your project with the following contents:

index.js
import { registerRootComponent } from 'expo';
import { ExpoRoot } from 'expo-router';

// Must be exported or Fast Refresh won't update the context
export function App() {
  const ctx = require.context('./app');
  return <ExpoRoot context={ctx} />;
}

registerRootComponent(App);

Do not use this to change the root directory (app) as it won't account for usage in any other places.

require.context not enabled

This can happen if you are using an expo version lower than expo@^46.0.13. Version 46.0.13 enables context modules and injects process.env.EXPO_ROUTER_APP_ROOT into the process.

This can also be the result of using a custom version of @expo/metro-config that does not enable context modules. Expo Router requires the project metro.config.js to use expo-router/metro as the default configuration. Delete the metro.config.js, or extend expo/metro-config. See Customizing metro for more information.