Can't serve express app on firebase functions emulator | EADDRINUSE: address already in use :::3000

Issue

I am testing express app deployment on firebase using firebase functions.
But after using the command firebase serve. I am getting EADDRINUSE: address already in use :::3000. Here is my index.js

const functions = require('firebase-functions');
const express = require('express');
const validator = require('email-validator');
const PORT = 3000;
const app = express();

/* JSON body parse*/
const bodyParser = require('body-parser');
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());

app.get('/hello', (req, res, next) => {
  console.info('/hello call success ');
  res.send('Welcome to Firebase Cloud Functions');
});

app.post('/emailValidate', async (req, res, next) => {
  const postData = req.body;
  if (postData.email) {
    console.info('/emailValidate call success ');
    res.json({ 'status': validator.validate(postData.email) });
  } else {
    console.warn('/emailValidate wrong input ');
    res.status(500).json({ 'status': 'wrong input' });
  }
});


app.listen(PORT, () => {
  console.info('Server is running on PORT:', PORT);
});

exports.app = functions.https.onRequest(app);    

package.json

{
  "name": "functions",
  "description": "Cloud Functions for Firebase",
  "scripts": {
    "serve": "firebase emulators:start --only functions",
    "shell": "firebase functions:shell",
    "start": "npm run shell",
    "deploy": "firebase deploy --only functions",
    "logs": "firebase functions:log"
  },
  "engines": {
    "node": "16"
  },
  "main": "index.js",
  "dependencies": {
    "body-parser": "^1.19.1",
    "email-validator": "^2.0.4",
    "express": "^4.17.2",
    "firebase-admin": "^9.8.0",
    "firebase-functions": "^3.14.1"
  },
  "devDependencies": {
    "firebase-functions-test": "^0.2.0"
  },
  "private": true
}

Error while opening URL functions[us-central1-app]: http function initialized (http://localhost:5001/{app-name}/us-central1/app).

 node:events:368
>        throw er; // Unhandled 'error' event
>        ^
>
>  Error: listen EADDRINUSE: address already in use :::3000
>      at Server.setupListenHandle [as _listen2] (node:net:1334:16)
>      at listenInCluster (node:net:1382:12)
>      at Server.listen (node:net:1469:7)
>      at Function.listen (\home\development\express-firebase\functions\node_modules\express\lib\application.js:618:24)
>      at Object.<anonymous> (D:\002_Research_Development\Web\development\express-firebase\functions\index.js:29:5)
>      at Module._compile (node:internal/modules/cjs/loader:1101:14)
>      at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
>      at Module.load (node:internal/modules/cjs/loader:981:32)
>      at Function.Module._load (node:internal/modules/cjs/loader:822:12)
>      at Module.require (node:internal/modules/cjs/loader:1005:19)
>  Emitted 'error' event on Server instance at:
>      at emitErrorNT (node:net:1361:8)
>      at processTicksAndRejections (node:internal/process/task_queues:83:21) {
>    code: 'EADDRINUSE',
>    errno: -4091,
>    syscall: 'listen',
>    address: '::',
>    port: 3000
>  }

Also, I have checked already there was nothing running at the defined PORT. Even tried changing the PORT number in index.js but the issue persist.

Any help would be much appreciated. 🙂

Solution

Another application is using port 3000, you need to stop the application and/or kill the port which varies depending on your operating system.

Answered By – destroyer22719

This Answer collected from stackoverflow, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0