MongoNetworkError: failed to connect to server [localhost:27017] on first connect [MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017]

Question

I'm new in nodeJS, started learning by following a trailer on youtube, everything goes well until I added the connect function if mongodb,

mongo.connect("mongodb://localhost:27017/mydb") 

when I run my code on cmd (node start-app), get the following error,

MongoNetworkError: failed to connect to server [localhost:27017] on first connect [MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017] 

Could someone explain me which step I missed ? my code :

var express = require("express"); var MongoClient = require('mongodb'); var url = "mongodb://localhost:27017/mydb"; var webService = require("./webService"); var server = express();  MongoClient.connect(url, function (err, db) {     if (err) throw err;     console.log("Database created!");     db.close(); });  server.use(express.urlencoded({ extended: true }));  server.set('views', __dirname);  server.get('/', function (request, response) {     response.sendFile(__dirname + '/MainPage.html'); });  server.get('/Sign', function (request, response) {     response.render(__dirname + '/Sign.ejs'); });  server.post("/signUp", webService.signUp);  server.post("/createUser", webService.createUser);  server.listen(5500); 

Answer 1

Many of them don't add this, especially in AWS EC2 Instance, I had the same issue and tried different solutions. Solution: one of my database URL inside the code was missing this parameter 'authSource', adding this worked for me.

mongodb://myUserName:MyPassword@ElasticIP:27017/databaseName?authSource=admin