How to fix “EADDRINUSE: address already in use” on Mac

By techynAR · Updated 23 October 2026

Short answerEADDRINUSE: address already in use :::3000 means another process is already listening on port 3000. On a Mac, run lsof -nP -iTCP:3000 -sTCP:LISTEN to see which process it is, then kill <PID> to stop it, or start your server on a different port. Portmole shows the same process in your menu bar and closes it in one click.

What the error means

Only one process can listen on a given port at a time. When your dev server (Node, Vite, Next.js, Express, Rails, Django and so on) tries to bind a port that something else already holds, the operating system refuses and Node prints Error: listen EADDRINUSE: address already in use :::3000. The :::3000 is port 3000 on all IPv6 and IPv4 addresses.

Nine times out of ten the “something else” is your own earlier server: a terminal tab you forgot about, an editor that started it in the background, or a crashed process whose child kept running.

Step 1: find what is using the port

lsof -nP -iTCP:3000 -sTCP:LISTEN

The output lists the command name (often node), its PID and the user. If nothing is printed, the port is free or the process belongs to another user, in which case rerun the command with sudo.

Step 2: stop it

kill 12345

Replace 12345 with the PID from step 1. kill sends SIGTERM, which asks the process to shut down cleanly. If it is still listening a few seconds later, force it with kill -9 12345. To do both steps at once:

kill $(lsof -t -iTCP:3000 -sTCP:LISTEN)

Or use a different port

If the old process is something you want to keep, start your server elsewhere instead. Most tools take a --port flag or a PORT environment variable. Our guide to running a dev server on another port has the exact flag for each framework.

Why it keeps happening

• You closed the terminal window but the server kept running as an orphan.
• A watcher or build tool restarted the server while the old one was still shutting down.
• Two projects are configured for the same default port.
• On macOS, ports 5000 and 7000 are taken by AirPlay Receiver (see the separate post on that).

The no-terminal way

Portmole is a free macOS menu bar app that lists every process listening on a port and closes it with one click, so you don't need to remember any of these commands. Open it, find :3000, click ✕.