Troubleshooting and Debugging React Native

console.log

Enable console.logs for React Native

1# run this command (when the app is running) to enable React Native logging
2# You only need to run this once and it'll be enabled for all future apps as well
3
4npx react-native log-ios
5npx react-native log-android

adb logs

You can start adb logging in another Terminal window

1# For a steady stream of constant logging
2adb logcat
3
4# filter React related logs
5adb logcat '*:S ReactNative:V ReactNativeJS:V'

Common Errors

White screen of death

You get an empty blank screen and no errors..

Chances are you ran react-native run-android first and then react-native start.

What you gotta do is close the app. Run react-native start and then in another terminal, run react-native run-android. You have to run react-native run-android in a separate terminal because you don’t get the prompt back when running react-native start

Could not connect to development server 500 -OR- SHA-1 ReferenceError

The development server returned response error code: 500

error: ReferenceError: SHA-1 for file node/v12.18.0/lib/node_modules/react-native/node_modules/metro/src/lib/polyfills/require.js (node/v12.18.0/lib/node_modules/react-native/node_modules/metro/src/lib/polyfills/require.js) is not computed

Turns out i had react-native insatlled globally instead of react-native-cli. If you have both react-native and react-native-cli installed, it’ll be messed up..

Solution is simple

1npm uninstall -g react-native
2npm i -g react-native-cli
3
4# OR
5
6yarn global remove react-native
7yarn global add react-native-cli

Or just use npx.

Links

• Docs: Debugging