` // server/index.js

const express = require("express");

const PORT = process.env.PORT || 3001;

const app = express();

app.get("/api", (req, res) => {
    res.json({ message: "Hello from Express!" });
  });

  app.listen(PORT, () => {
     console.log(`Server listening on ${PORT}`);
  });

app.listen(PORT, () => {
  console.log(`Server listening on ${PORT}`);
});

npm start   

> [email protected] start
> node server/index.js

Server listening on 3001
node:events:496
      throw er; // Unhandled 'error' event
  ^

Error: listen EADDRINUSE: address already in use :::3001
at Server.setupListenHandle [as _listen2] (node:net:1897:16)
at listenInCluster (node:net:1945:12)
at Server.listen (node:net:2037:7)
at Function.listen (C:UserssrushDesktopreact-node-appnode_modulesexpresslibapplication.js:635:24)
at Object. (C:UserssrushDesktopreact-node-appserverindex.js:17:5)
at Module._compile (node:internal/modules/cjs/loader:1369:14)
at Module._extensions..js (node:internal/modules/cjs/loader:1427:10)
at Module.load (node:internal/modules/cjs/loader:1206:32)
at Module._load (node:internal/modules/cjs/loader:1022:12)
at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:135:12)
at process.processTicksAndRejections (node:internal/process/task_queues:82:21) {
code: ‘EADDRINUSE’,
errno: -4091,
syscall: ‘listen’,
address: ‘::’,
port: 3001
}

Node.js v20.12.1your text
PS C:UserssrushDesktopreact-node-app> taskkill /f/im server.js
ERROR: Invalid argument/option – ‘/f/im’.
Type “TASKKILL /?” for usage.`