Replit error: "EADDRINUSE: address already in use"

What it means

Your app is trying to start on a port (like a door number) that's already taken, usually because an old copy of your app is still running.

How to fix it

1. Click Stop, wait a few seconds, then click Run again.
2. If that doesn't work, open the Shell and run kill 1 to restart the Repl.
3. Ask Replit's AI: "Make the server listen on process.env.PORT || 3000 and bind to 0.0.0.0."

FAQ

What does "port already in use" mean in Replit?

An old copy of your app is still running on that port, so the new one can't start.

How do I fix EADDRINUSE in Replit?

Click Stop, wait a few seconds, and Run again. If that fails, run kill 1 in the Shell to restart the Repl.

What port should my Replit app use?

Use process.env.PORT || 3000 and bind to 0.0.0.0 so Replit can reach it.