troubleshooting

12 notes, read out of this brain and free to use. Each one was extracted from a source and is re-checked against its exam.

Metro bundler ECONNREFUSED 127.0.0.1:19001 error diagnosis

The Metro bundler ECONNREFUSED 127.0.0.1:19001 error occurs when an error is preventing the connection to your local development server. To debug this error, run 'rm -rf .expo' to clear your local state and check for firewalls or proxies affecting the network you are currently connected to.

Module AppRegistry not registered callable module error

The 'Module AppRegistry is not a registered callable module (calling runApplication)' error occurs when an error in your code is preventing the JavaScript bundle from being executed on startup. To debug this, run 'npx expo start --no-dev --minify' to reproduce the production JS bundle locally. Connect your device and access device logs via Android Studio or Xcode for detailed stacktraces. Check for any changes or errors in your Babel configuration. In rare cases, this could be caused by incompatibility between the Metro JavaScript minifier and certain code in your app.

npm ERR No git binary found in $PATH error

The 'npm ERR! No git binary found in $PATH' error occurs when either git is not installed or it is not properly configured in your $PATH. To fix this, install git if you have not already, otherwise check how to set it in your $PATH based on your operating system.

Application not behaving as expected error

The 'Application not behaving as expected' error can occur when caches are preventing you from seeing the current state of your application. To fix this, clear all caches associated with your project in Unix-like or Windows systems.

React Native version mismatch error

The 'React Native version mismatch' error occurs when the development server running in your terminal is bundling a different version of React Native than the app in your device or simulator. To fix this, align your versions of react-native by checking the versions in your app.json and package.json files.

Application has not been registered error

The 'Application has not been registered' error occurs when there is a mismatch between the AppKey registered in the native and JavaScript portion of your app. To fix this, align your AppKey with the native side of your project.

XX.X.X is not a valid SDK version error

The 'XX.X.X is not a valid SDK version' error occurs when the SDK version you are running has been deprecated and is no longer supported. To fix this, upgrade your project to a supported SDK version. If you are using a supported version and still see this message, you need to update your Expo Go app.

Simulator Expo Go app not opening on first install

The first time you install the Expo Go app in the simulator, iOS will ask if you would like to open it. You may need to interact with the simulator (click around, drag something) for this prompt to show up, then press OK.

Manual iOS Simulator launch

If the iOS Simulator doesn't respond to the open command or seems stuck, you can open it manually using open -a Simulator. Then in the macOS toolbar, choose File > Open Simulator to select an iOS version and device. You can open multiple simulators at the same time, but Expo CLI will always target the most recently opened simulator.

Installing specific version of Expo Go

You can create a project with the desired SDK version (e.g., npx create-expo-app --template blank@57) and open it in a simulator to install the matching version of Expo Go. Alternatively, use the expo-go CLI to download a specific version: npx expo-go download ios latest (or specify an SDK version instead of 'latest').

Fixing xcrun errors in Expo CLI

If Expo CLI prints an error message about xcrun, try the following: manually uninstall Expo Go on your simulator and reinstall by pressing Shift + I in the Expo CLI Terminal UI and selecting the desired simulator. If that doesn't help, focus the simulator window and in the Mac toolbar choose Device > Erase All Content and Settings to reinitialize your simulator from a blank image. This is sometimes useful for cases where your computer is low on memory and the simulator fails to store some internal files, leaving the device in a corrupt state.

Check workflow run detail page for diagnostics

If a workflow doesn't start or a job fails, start with the workflow run's detail page on the project's workflows page. It shows each job's status, logs, and errors.

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