1---
2title: Troubleshooting
3description: Fixing common issues with Expo Router setup.
4---
5
6import { Terminal } from '~/ui/components/Snippet';
7
8## `EXPO_ROUTER_APP_ROOT` not defined
9
10If `process.env.EXPO_ROUTER_APP_ROOT` is not defined you'll see the following error:
11
12<Terminal
13  cmd={[
14    '$ Invalid call at line 11: process.env.EXPO_ROUTER_APP_ROOT First argument of require.context should be a string.',
15  ]}
16/>
17
18This can happen when:
19
20- 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.
21- The babel plugin `expo-router/babel` is not being used in the project **babel.config.js**. You can try clearing the cache with:
22
23<Terminal cmd={['$ npx expo start --clear']} />
24
25Alternatively, you can circumvent this issue by creating an **index.js** file in the root of your project with the following contents:
26
27```jsx index.js
28import { registerRootComponent } from 'expo';
29import { ExpoRoot } from 'expo-router';
30
31// Must be exported or Fast Refresh won't update the context
32export function App() {
33  const ctx = require.context('./app');
34  return <ExpoRoot context={ctx} />;
35}
36
37registerRootComponent(App);
38```
39
40> Do not use this to change the root directory (**app**) as it won't account for usage in any other places.
41
42## `require.context` not enabled
43
44This 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.
45
46This 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](/guides/customizing-metro/) for more information.
47