MongoParseError: Options useCreateIndex and useFindAndModify Not Supported

Problem Statement

When connecting to MongoDB using Mongoose, you may encounter a MongoParseError with the message that options useCreateIndex and useFindAndModify are not supported. This typically occurs when using Mongoose version 6 or later with connection options that were valid in earlier versions but have been deprecated.

// This will cause MongoParseError in Mongoose 6+
const URI = process.env.MONGODB_URL;

mongoose.connect(URI, {
   useCreateIndex: true, 
   useFindAndModify: false, 
   useNewUrlParser: true, 
   useUnifiedTopology: true 
}, err => {
   if(err) throw err;
   console.log('Connected to MongoDB!!!')
});

Why This Error Occurs

Starting with Mongoose 6, several connection options have been removed because their functionality is now enabled by default:

• useNewUrlParser and useUnifiedTopology are always true
• useCreateIndex is always true
• useFindAndModify is always false

These options are no longer necessary and will cause a parsing error if included in your connection configuration.

Solution

Remove the deprecated options from your Mongoose connection configuration. Here's the updated code:

const URI = process.env.MONGODB_URL;

// Simple connection without deprecated options
mongoose.connect(URI)
  .then(() => console.log('Connected to MongoDB successfully!'))
  .catch(error => console.error('Connection error:', error));

Using async/await Syntax

const connectDB = async () => {
  try {
    await mongoose.connect(process.env.MONGODB_URL);
    console.log('MongoDB connected successfully');
  } catch (error) {
    console.error('Database connection failed:', error.message);
    process.exit(1);
  }
};

connectDB();

With Event Listeners

const URI = process.env.MONGODB_URL;

mongoose.connect(URI);

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

connection.on('error', (err) => {
  console.error('Connection error:', err);
});

Migration Guide

If you're upgrading from Mongoose 5 to Mongoose 6, make the following changes:

Before Mongoose 6

mongoose.connect(URI, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
  useCreateIndex: true,
  useFindAndModify: false
});

Mongoose 6+

mongoose.connect(URI);

Additional Considerations

Strict Query Mode

Mongoose 6 enables strict query mode by default. If you need to maintain backward compatibility with existing queries, you can disable it:

mongoose.set("strictQuery", false);

Callback Syntax Changes

Mongoose 6 uses promises instead of callbacks for connections. The callback syntax is no longer supported:

// No longer works in Mongoose 6
mongoose.connect(URI, (err) => {
  if (err) throw err;
  console.log('Connected');
});

Environment Configuration

Ensure your MongoDB connection string in your .env file is properly formatted:

MONGODB_URL=mongodb+srv://username:password@cluster0.accdl.mongodb.net/website?retryWrites=true&w=majority

WARNING

Always keep sensitive information like database credentials in environment variables rather than hardcoding them in your application.

Version Compatibility

This solution applies to:

• Mongoose version 6.0.0 and later
• MongoDB Node.js driver 4.0.0 and later
• MongoDB server versions 4.0, 4.2, 4.4, 5.0, and later

Conclusion

The MongoParseError regarding useCreateIndex and useFindAndModify options is resolved by removing these deprecated configuration options from your Mongoose connection setup. Mongoose 6 simplifies connection configuration by making these options the default behavior, resulting in cleaner, more maintainable code.

For more information, refer to the official Mongoose migration guide.