"Error: listen EADDRINUSE: address already in use :::3000" means another process is already listening on port 3000, so your Node. js server can't bind to it. The quick fix on Linux or macOS is to find that process with lsof -i :3000 and stop it with kill <PID> .
Source: [Dev.to](https://dev.to/mfaysaldev/error-listen-eaddrinuse-address-already-in-use-in-nodejs-10-causes-and-fixes-tested-on-linux-5kf)