How to Fix Connection Refused Error in MongoDB

The connection refused error in MongoDB usually means the MongoDB server is not running or not reachable. To fix it, ensure the MongoDB service is started, the connection string is correct, and no firewall blocks the port (default 27017).

Why This Happens

This error happens when your application tries to connect to MongoDB but cannot reach the server. Common reasons include the MongoDB server not running, using the wrong port or IP address, or network/firewall blocking the connection.

javascript

const { MongoClient } = require('mongodb');

async function connect() {
  const client = new MongoClient('mongodb://localhost:27018'); // Wrong port
  await client.connect();
  console.log('Connected to MongoDB');
}

connect().catch(console.error);

Output

MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27018

The Fix

Start the MongoDB server if it is not running. Use the correct connection string with the right port (default is 27017). Also, check that no firewall or network setting blocks the connection.

javascript

const { MongoClient } = require('mongodb');

async function connect() {
  const client = new MongoClient('mongodb://localhost:27017'); // Correct port
  await client.connect();
  console.log('Connected to MongoDB');
  await client.close();
}

connect().catch(console.error);

Output

Connected to MongoDB

Prevention

Always verify MongoDB server status before connecting. Use monitoring tools or commands like mongod --version or systemctl status mongod. Keep your connection strings updated and avoid hardcoding ports. Configure firewalls to allow MongoDB traffic on port 27017.

Related Errors

• Authentication failed: Check username and password in connection string.
• Timeout error: Network is slow or server is overloaded.
• DNS resolution error: Hostname in connection string is incorrect.

Key Takeaways

Ensure MongoDB server is running before connecting.

Use the correct connection string with the right port (default 27017).

Check firewall and network settings to allow MongoDB traffic.

Avoid hardcoding connection details; use environment variables.

Monitor server status regularly to prevent connection issues.