Port 5000 in use on Mac? It’s AirPlay Receiver

• Flask: Address already in use. Port 5000 is in use by another program. Recent versions add a hint about AirPlay Receiver.
• Docker: Ports are not available: exposing port TCP 0.0.0.0:5000 -> 0.0.0.0:0: listen tcp 0.0.0.0:5000: bind: address already in use
• ASP.NET, a local Docker registry (registry:2) or anything else that defaults to 5000 fails the same way.
• Opening http://localhost:5000 shows 403 Forbidden and an empty page, even with your server stopped.

lsof -nP -iTCP:5000 -sTCP:LISTEN

COMMAND   PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
ControlCe 423 you    9u  IPv4  0x2f88…      0t0  TCP *:5000 (LISTEN)
ControlCe 423 you   10u  IPv6  0x7a41…      0t0  TCP *:5000 (LISTEN)

ControlCe is ControlCenter, cut to nine characters. To be sure it’s the AirPlay server and not something else, look at the Server header:

curl -sI http://localhost:5000 | grep -i server

Server: AirTunes/…

AirTunes is the AirPlay receiver. If you see another name instead, it’s a real leftover process: follow Port already in use on a Mac.

1. Open System Settings → General → AirDrop & Handoff.
2. Switch off AirPlay Receiver.
3. Run lsof -nP -iTCP:5000 -sTCP:LISTEN again: it prints nothing, and port 5000 is yours.

This frees 7000 too. You lose the ability to AirPlay from an iPhone or another Mac to this Mac; streaming from this Mac to a TV or speaker still works. Switch it back on whenever you need it.

If you use AirPlay Receiver, leave it on and move your app. 5001 is the usual choice:

flask run --port 5001
python app.py                       # with app.run(port=5001)
docker run -p 5001:5000 my-image     # host 5001 → container 5000
dotnet run --urls http://localhost:5001

With Docker, only the left side of -p changes: the app inside the container keeps listening on 5000. In Compose that’s ports: ["5001:5000"]. For a team that mixes Macs and other machines, make the port an environment variable, for example FLASK_RUN_PORT=5001 in .flaskenv.

AirPlay Receiver holds 7000 as well, which bites Cassandra (inter-node traffic), some Django and Node setups, and anything that picked 7000 to stay clear of 5000. The fixes are the same: turn the receiver off, or move to 7001 or above.

With Show system processes on, Portlivo lists ControlCenter on 5000 and 7000 next to your dev servers, so a taken port has a name before you start anything. When a server you started from Portlivo can’t bind its port, the notification says what holds it.