Fix EADDRINUSE: address already in use (Node.js on Mac)

You start your Node dev server and get this error. It means another process already listens on that port.

Error: listen EADDRINUSE: address already in use :::3000

What it means

Only one program can listen on a port at a time. EADDRINUSE is the error code for address in use, and :::3000 is port 3000 on all addresses. Most often the culprit is an earlier run of your own server that you forgot about.

Fix 1: stop the old process

lsof -nP -iTCP:3000 -sTCP:LISTEN
kill $(lsof -ti tcp:3000 -sTCP:LISTEN)

The first line shows what holds the port, the second stops it. Start your server again.

Fix 2: use a different port

PORT=3001 npm run dev
npx next dev -p 3001
npx vite --port 3001

PORT only works if your project reads it. Next.js reads it; Vite takes its own flag.

Common causes on a Mac

• A dev server you started earlier and forgot: another Terminal tab, a background job or an editor task.
• A crashed run that left a child process behind. The parent died, the child kept the port.
• A Docker container that publishes the port. Check with docker ps --filter publish=3000.
• AirPlay Receiver. On recent macOS versions it listens on ports 5000 and 7000. If your error says 5000 or 7000, turn it off in System Settings, General, AirDrop & Handoff, AirPlay Receiver.

Check that it is free

lsof -nP -iTCP:3000 -sTCP:LISTEN

No output means nothing is listening and your server can start.

More guides

• Kill the process on port 3000
• What is running on a port
• Rungeist for Mac