Mongodb Connection Error: Mongotimeouterror: Server Selection Timed out After 30000 Ms

just go to mongodb atlas admin panel.Go in security tab>Network Access> Then whitelist your IP by adding it

See this image to locate the particular menu

Note:Check your IP on google then add it

Sometimes this error occurs due to the IP Address given access to in our database.

Mind you, your application can be working well then come up with such an error. Anytime this happens, most times your IP address has changed, which is not on the whitelist of addresses allowed. (IP addresses can be dynamic and are subject to change)

All you have to do is to update the whitelist with your current IP addresses

Ensure that the "<" and ">" are removed when you replace the user and password fields. This worked for me

I got the same error. These are the steps I followed for resolve it

1. Log into your Mongo Atlas account
2. Go to the security tab -> Network Access -> Then whitelist your IP
3. Then go to the security tab -> Database Access -> and delete your current user.
4. Create a new user by providing new username and password.
5. Provide that newly created username and password in the .env file or mongoose.connect method

After these steps it worked as usual. hope this will help you guys.

I wasted whole day on this because the whitelist suggestion was not my issue (I'm running in docker compose with --bind_ip option set properly and I can see the Connection accepted in the mongo logs each time my client tried to connection).

It turns out, I simply needed to add this to the end of my connection string in the code:

?directConnection=true

connection string:

mongodb://myUserId:myPassword@mongodb/myDatabase?directConnection=true

I hope mongodb documents this better because I only stumbled across it from looking at the mongosh logs when I connected using that client.

Sometimes it will also happen when your MongoDB services are turned OFF.

Here are the steps to Turn ON the MongoDB Services:

1. Press window key + R to open Run window.
2. Then type services.msc to open services window.
3. Then select MongoDB server, right-click on it, finally click on the start.

Whitelist your connection IP address. Atlas only allows client connections to the cluster from entries in the project’s whitelist. The project whitelist is distinct from the API whitelist, which restricts API access to specific IP or CIDR addresses.

NOTE

You can skip this step if Atlas indicates in the Setup Connection Security step that you have already configured a whitelist entry in your cluster. To manage the IP whitelist, see Add Entries to the Whitelist.

If the whitelist is empty, Atlas prompts you to add an IP address to the project’s whitelist. You can either:

Click Add Your Current IP Address to whitelist your current IP address.

Click Add a Different IP Address to add a single IP address or a CIDR-notated range of addresses.

For Atlas clusters deployed on Amazon Web Services (AWS) and using VPC Peering, you can add a Security Group associated with the peer VPC.

You can provide an optional description for the newly added IP address or CIDR range. Click Add IP Address to add the address to the whitelist.

Are you using any Antivirus, Firewall, VPN or on the restricted network (e.g. work/commercial Wi-Fi/LAN connection)? Then try to turn it off/reconnect to a different network. Some IPs/connections might be blocked by the administrator of a network that you're using or simply antivirus might have firewall policies. Even though if you have 0.0.0.0 in your IP Address at the MongoDB Atlas.

You can remove { useUnifiedTopology: true } flag and reinstall mongoose dependecy! it worked for me.

To anyone still struggling through this issue. I resolved this issue by setting all the parameters like username, password and dbName in mongoose options itself.

Earlier the code was like this. (When I was getting the error).

import mongoose from "mongoose";
mongoose.Promise = require("bluebird");

let dbName = process.env.DB_NAME;
const dbAddress = process.env.DB_HOST;
const dbPort = process.env.DB_PORT;
if(!dbName || !dbAddress || !dbPort){
    throw new Error("Mongo error unable to configuredatabase");
}

let options = {
    useNewUrlParser: true,
    useUnifiedTopology: true,
    user:process.env.DB_USER,
    pass: process.env.DB_PASS
};

mongoose.connect(`mongodb://${dbAddress}:${dbPort}/${dbName}`, options).catch(err => {
    if (err.message.indexOf("ECONNREFUSED") !== -1) {
        console.error("Error: The server was not able to reach MongoDB. Maybe it's not running?");
        process.exit(1);
    } else {
        throw err;
    }
});

Note that url in mongo connect. mongodb://${dbAddress}:${dbPort}/${dbName}.

New code without error.

import mongoose from "mongoose";
mongoose.Promise = require("bluebird");

let dbName = process.env.DB_NAME;
const dbAddress = process.env.DB_HOST;
const dbPort = process.env.DB_PORT;
// console.log("process.env", process.env)
if(!dbName || !dbAddress || !dbPort){
    throw new Error("Mongo error unable to configuredatabase");
}

let options = {
    useNewUrlParser: true,
    useUnifiedTopology: true,
    user:process.env.DB_USER,
    pass: process.env.DB_PASS,
    dbName: dbName
};

mongoose.connect(`mongodb://${dbAddress}:${dbPort}`, options).catch(err => {
    if (err.message.indexOf("ECONNREFUSED") !== -1) {
        console.error("Error: The server was not able to reach MongoDB. Maybe it's not running?");
        process.exit(1);
    } else {
        throw err;
    }
});

Note the options and the url.

This is my local env. Not production env.

Hope It'll be helpful.

try to specify the node driver, version 2,2,12 in cluster --> connect --> connect your application. new string must be with mongodb://. use this string to connect. do not forget to enter a password

In my case, this issue happened after NodeJS version upgrade from Node 14 to Node 17 and the mongoose was not connecting to MongoDB in local.

Solution - In connection string, change localhost to 127.0.0.1.

Ref -

i was has this problem, to me the solution was check if my ip be configured correctly and before confirm in this screen

enter image description here

Please Check your Password, Username OR IP configuration. Mostly "Server selection timed out after 30000 ms at Timeout._onTimeout" comes whenever your above things are not matched with your server configuration.

I am able to solve the issue. Everything was fine, but the firewall was blocking access to port 27017. connectivity can be tested at or using telnet to the endpoint which can be retrieved from clusters->Metrics.

Thanks, everybody for the suggestions

Try to make new User in Database Access with the default Authentication Method which is "SCRAM". Then make a new Cluster for that. It worked for me! My server.js file

const express = require('express');
const cors = require('cors');
const mongoose = require('mongoose');

require('dotenv').config();

const app = express();
const port = process.env.PORT || 5000;

app.use(cors());
app.use(express.json());

//const uri = process.env.ATLAS_URI;
mongoose.createConnection("mongodb+srv://u1:u1@", { userNewParser: true, useCreateIndex: true,  useUnifiedTopology: true}
    );

const connection = mongoose.connection;
connection.once('once', () => {
    console.log(`MongoDB databse connection established successfully`);
})

app.listen(port, () => {
    console.log(`Server is running on port: ${port}`);
});

What is your mongoose version? because there is an issue with a certain mongoose version. Please visit this link for more details "". Anyway, I was facing the same issue but after using an older version (5.5.2), it worked for me. Please give a try and let me know what happened.

It might basically be because of an npm update. I just updated to npm v 6.13.7. and I began to get that error.

Following instructions from @Matheus, I commented the line "{ useUnifiedTopology: true }" and I was able to get through it.

I updated mongoose and everything works fine.

I had the same issue. I could connect from MongoDB Compass or my Node app using the connection strings Atlas gave me. I resolved it by adding my IP Address into the Whitelist in Atlas.

Official documentation from MongoDB - How do I connect to an Atlas cluster over an SSH tunnel?

Newer versions of Mongoose and MongoDB require your application port higher than 5000.

If your app running on port 3000 for example, you'll have this error message.

I just changed my PORT from 3000 to 5556 and I'm fine 🎉