I came across this cannot GET /debugger-ui react native error when I was trying to debug one of my react native projects. It showed just Cannot GET /debugger-ui/ on my browser whereas in the device I got the following error message.
Failed to connect to debugger!
Timeout while connecting to remote debugger
I tried reloading the project using developer tools but the error didn’t go. Then I restarted the metro bundler with react-native start command. Also, rerun the project with react-native run-android . After that, I was able to debug my project without errors.