Overview

MacOS Monterey (version 12) is the 18th and current major release of macOS. The successor to macOS Big Sur, it was announced at WWDC 2021 on June 7, 2021, and was officially released on October 25, 2021. Every update of Macintosh comes with some surprises and nightmares(this time address already in use).

In this blog, I’m not talking about all the good thing that has been introduced in the new release but will be talking about one thing that is super annoying for every developer. This new version of macOS has “hijacked our cute little port — 5000” from us.

5000 port already in use by MacOS

Yeah you heard this right, from ages developers are using this 5000 port for local development and now it’s like a default thing for any local server. You’ll get an error as below. As of macOS ControlCe service is listening of the port.

OSError: [Errno 48] Address already in use

Issue

Run a Flask server or any server of your choice

Run the simple flask server using

python app.py

Then you must be seeing something like below

File "/usr/local/Cellar/python@3.9/3.9.7/Frameworks/Python.framework/Versions/3.9/lib/python3.9/socketserver.py", line 452, in __init__
    self.server_bind()
  File "/usr/local/Cellar/python@3.9/3.9.7/Frameworks/Python.framework/Versions/3.9/lib/python3.9/http/server.py", line 138, in server_bind
    socketserver.TCPServer.server_bind(self)
  File "/usr/local/Cellar/python@3.9/3.9.7/Frameworks/Python.framework/Versions/3.9/lib/python3.9/socketserver.py", line 466, in server_bind
    self.socket.bind(self.server_address)
OSError: [Errno 48] Address already in use

This error is coming because the port that we are using for the local server is actually in use by MacOS

Solution

Simple solution is just use some other port instead of 5000 or else follow the below steps.

Step 1

Open system preferences

Step 2

Then open Sharing

Step 3

Uncheck Airplay Receiver, as Airplay receiver is using that port

Run the server again!!

Conclusion

I hope, it has helped you. If you want to discuss anything or anything related to tech, you can contact me here or on my personal blog Progress Story. See you next time. Peace out!