When trying to run an app if you are getting the error “Unable to bind: Address already in use”, you can use this command on linux to check which process is already using that port:
netstat -tulpn
Then you can kill the process with:
kill <pid>
If you are on windows you can check the port usage with:
netstat -a -o -n
And kill process on windows with:
taskkill /F /PID <pid>