The following error can be encountered when running multiple servers:
> Error: Address already in use
> Error: listen EADDRINUSE
This is because the port has already been bound to a running server and now another server is trying to listen on that port.
There are 2 things that can be done:
- Start your server on a different port.
- Or free the port by killing the process associated with it.
Warning: If you choose the 2nd option, make sure you’re not killing anything important.
Getting the pid
Use lsof to get the process id (pid) associated with the port:
lsof -ti :<PORT>
Replace
<PORT>with the port number.
Killing the pid
To kill the process associated with the port:
kill $(lsof -ti :<PORT>)
There may be a scenario where you’ll need to pass the SIGKILL signal to stop and kill the process immediately:
kill -9 $(lsof -ti :<PORT>)
Use sudo if you don’t have permissions:
sudo kill -9 $(lsof -ti :<PORT>)
And Unix users can accomplish the same thing with fuser:
fuser -k <PORT>/tcp