What does EADDRINUSE mean on Mac?

Another process is already listening on that port, usually an old dev server. Find it with lsof -nP -iTCP:PORT -sTCP:LISTEN and stop it with kill PID.

Dhiru · dev watch

"Address already in use" on Mac: how to fix EADDRINUSE

Error: listen EADDRINUSE: address already in use :::3000 (or Python's OSError: [Errno 48] Address already in use) means something is already listening on that port. Usually it's an older copy of the same dev server, left running in another terminal tab or after an editor crash.

Find it (use your port):

lsof -nP -iTCP:3000 -sTCP:LISTEN

Stop it:

kill <PID>

If lsof shows ControlCenter on 5000 or 7000, that's macOS's AirPlay Receiver. Turn it off in System Settings → General → AirDrop & Handoff, or use a different port.

Stop it happening again

Stop dev servers with Ctrl-C rather than closing the terminal window, and check what's still listening before you start a new one: lsof -nP -iTCP -sTCP:LISTEN.