Error: listen EADDRINUSE

Linux / macOS

1. lsof -i :3000
2. kill -9
3. Or use: npx kill-port 3000

Windows (PowerShell)

1. netstat -ano | findstr :3000
2. taskkill /F /PID
3. Or use: npx kill-port 3000

• If lsof shows no process on the port → The port may be in TIME_WAIT. Wait 60 seconds or restart with a different port.
• If The PID belongs to a system process (PID < 1000) → Choose a different port. System services on low ports require root to override.
• If Happens every time you restart your dev server → Add a graceful shutdown handler: process.on("SIGTERM", () => server.close())

• Port held by a process in TIME_WAIT state: wait 30–60 seconds or use SO_REUSEADDR in your server options
• WSL2 port conflict with Windows host: check both WSL and Windows processes on the same port
• Docker port mapping collision: docker ps may reveal a container already bound to the port

const server = app.listen(3000, () => {
  console.log("Server running on port 3000");
});

process.on("SIGTERM", () => server.close());
process.on("SIGINT", () => server.close());