Fix 'MongoNetworkError: connect ECONNREFUSED' in Node.js

ECONNREFUSED from MongoDB means your driver reached an address but nothing answered. With Atlas it is almost always the IP allowlist; locally it is usually the service not running.

Local MongoDB: Is It Running?

# macOS (Homebrew)
brew services start mongodb-community

# Linux
sudo systemctl start mongod
sudo systemctl status mongod

Atlas: Allowlist Your IP

In Atlas → Network Access, add your current IP. For a server with a changing IP, you may temporarily allow 0.0.0.0/0 (any IP) — but lock it down for production.

Verify the Connection String

// Use the SRV string for Atlas; URL-encode special characters in the password
const uri = process.env.MONGODB_URI; // mongodb+srv://user:pass@cluster.mongodb.net/db

await mongoose.connect(uri, { serverSelectionTimeoutMS: 5000 });