timeoutError - MongoServerSelectionError: connect ECONNREFUSED ::1:27017 - [NodeJS + MongoDB]

Question

Disclaimer: Similar topics did not offer a valid solution for my problem!

• Restarted MongoDB server (it keeps running when error occurs)
• Using MongoDB server on windows as a service (started it manually)
• Established the connection via MongoDB Shell CLI Package by hitting enter in the comand prompt to establish the default connection (mongodb://127.0.0.1:27017/directConnection=true&serverSelectionTimeoutMS=2000 )
• Called npm install and npm start (my dependencies are listed below)
• Checked that MongoDB is running
• Checked via the windows resource monitor that the port 27017 is occupied by mongod.exe using TCP and is not restricted by the firewall
• Checked that I am not using a VPN nor a proxy connection that could interfere.
• Then I opened http://localhost:3000/ to which I am listening (app.listen(3000);)

However, I still get the following error:

const timeoutError = new error_1.MongoServerSelectionError(`Server selection timed out after ${serverSelectionTimeoutMS} ms`, this.description);                                     ^
 
MongoServerSelectionError: connect ECONNREFUSED ::1:27017
    at Timeout._onTimeout (\node_modules\mongodb\lib\sdam\topology.js:330:38)
    at listOnTimeout (node:internal/timers:557:17)
    at processTimers (node:internal/timers:500:7) {
  reason: TopologyDescription {
    type: 'Unknown',
    servers: Map(1) {
      'localhost:27017' => ServerDescription {
        _hostAddress: HostAddress { isIPv6: false, host: 'localhost', port: 27017 },
        address: 'localhost:27017',
        type: 'Unknown',
        hosts: [],
        passives: [],
        arbiters: [],
        tags: {},
        maxWireVersion: 0,
        roundTripTime: -1,
        lastUpdateTime: 536295834,
        lastWriteDate: 0,
        error: MongoNetworkError: connect ECONNREFUSED ::1:27017
            at connectionFailureError (\node_modules\mongodb\lib\cmap\connect.js:293:20)
            at Socket.<anonymous> (\node_modules\mongodb\lib\cmap\connect.js:267:22)
            at Object.onceWrapper (node:events:510:26)
            at Socket.emit (node:events:390:28)
            at emitErrorNT (node:internal/streams/destroy:164:8)
            at emitErrorCloseNT (node:internal/streams/destroy:129:3)
            at processTicksAndRejections (node:internal/process/task_queues:83:21)
      }
    },
    stale: false,
    compatible: true,
    heartbeatFrequencyMS: 10000,
    localThresholdMS: 15,
    logicalSessionTimeoutMinutes: undefined
  }
}

My dependencies:

 "dependencies": {
    "ejs": "^3.1.6",
    "express": "^4.17.1",
    "mongodb": "^4.0.1"
  },
  "devDependencies": {
    "nodemon": "^2.0.7"
  }

FYI: Node.js v17.0.1

Update: Here is my database.js file

const mongodb = require('mongodb');

const MongoClient = mongodb.MongoClient;

let database;

async function connectToDatabase() {
  const client = await MongoClient.connect('mongodb://localhost:27017');
  database = client.db('file-demo');
}

function getDb() {
  if (!database) {
    throw { message: 'Database not connected!' };
  }
  return database;
}

module.exports = {
  connectToDatabase: connectToDatabase,
  getDb: getDb,
};

Here is my app.js:

const path = require('path');

const express = require('express');

const userRoutes = require('./routes/users');
const db = require('./data/database');

const app = express();

app.set('view engine', 'ejs');
app.set('views', path.join(__dirname, 'views'));

app.use(express.urlencoded({ extended: false }));
app.use(express.static('public'));

app.use(userRoutes);

db.connectToDatabase().then(function () {
  app.listen(3000);
});

Answer 1

As @prasad_ pointed out, it can help to change localhost to 127.0.0.1, in the file, in which you are establishing your connection to the MongoDB Server. Although they should be treated as synonyms and as I was able to rule out the general problems (which you can find as an answer in similar questions) this might just be a caching issue with chrome, like in here.

Answer 2

In my case I replaced the hostname

localhost

to

127.0.0.1

Try change from

async function connectToDatabase(){
const client = await MongoClient.connect('mongodb://localhost:27017');
 database = client.db('file-demo');
}

to

async function connectToDatabase() {
 const client = await MongoClient.connect('mongodb://127.0.0.1:27017');
 database = client.db('file-demo');
}