# Fix "Address Already in Use" Error

## What it means

This error happens when a program tries to bind to a port that another process is already using.

Example error:

`OSError: [Errno 98] Address already in use`

## Step 1 — Find the process using the port

Example for port 5000:

`lsof -i :5000`

Example output:

`python 1234 user  TCP *:5000 (LISTEN)`

## Step 2 — Stop the process

Kill the process using the PID:

`kill 1234`

If it refuses to stop:

`kill -9 1234`

## Alternative command

You can also use:

`sudo fuser -k 5000/tcp`

## Notes

- Very common when restarting web servers like Flask.
- Make sure you are killing the correct process.