Automattic/mongoose · error · MongooseError

Mongoose.prototype.connect() no longer accepts a callback

Error message

Mongoose.prototype.connect() no longer accepts a callback

What it means

Error "Mongoose.prototype.connect() no longer accepts a callback" thrown in Automattic/mongoose.

Source

Thrown at lib/mongoose.js:466

 * @param {string} [options.dbName] The name of the database we want to use. If not provided, use database name from connection string.
 * @param {string} [options.user] username for authentication, equivalent to `options.auth.username`. Maintained for backwards compatibility.
 * @param {string} [options.pass] password for authentication, equivalent to `options.auth.password`. Maintained for backwards compatibility.
 * @param {number} [options.maxPoolSize=100] The maximum number of sockets the MongoDB driver will keep open for this connection. Keep in mind that MongoDB only allows one operation per socket at a time, so you may want to increase this if you find you have a few slow queries that are blocking faster queries from proceeding. See [Slow Trains in MongoDB and Node.js](https://thecodebarbarian.com/slow-trains-in-mongodb-and-nodejs).
 * @param {number} [options.minPoolSize=0] The minimum number of sockets the MongoDB driver will keep open for this connection.
 * @param {number} [options.serverSelectionTimeoutMS] If `useUnifiedTopology = true`, the MongoDB driver will try to find a server to send any given operation to, and keep retrying for `serverSelectionTimeoutMS` milliseconds before erroring out. If not set, the MongoDB driver defaults to using `30000` (30 seconds).
 * @param {number} [options.heartbeatFrequencyMS] If `useUnifiedTopology = true`, the MongoDB driver sends a heartbeat every `heartbeatFrequencyMS` to check on the status of the connection. A heartbeat is subject to `serverSelectionTimeoutMS`, so the MongoDB driver will retry failed heartbeats for up to 30 seconds by default. Mongoose only emits a `'disconnected'` event after a heartbeat has failed, so you may want to decrease this setting to reduce the time between when your server goes down and when Mongoose emits `'disconnected'`. We recommend you do **not** set this setting below 1000, too many heartbeats can lead to performance degradation.
 * @param {boolean} [options.autoIndex=true] Mongoose-specific option. Set to false to disable automatic index creation for all models associated with this connection.
 * @param {number} [options.socketTimeoutMS=0] How long the MongoDB driver will wait before killing a socket due to inactivity _after initial connection_. A socket may be inactive because of either no activity or a long-running operation. `socketTimeoutMS` defaults to 0, which means Node.js will not time out the socket due to inactivity. This option is passed to [Node.js `socket#setTimeout()` function](https://nodejs.org/api/net.html#net_socket_settimeout_timeout_callback) after the MongoDB driver successfully completes.
 * @param {number} [options.family=0] Passed transparently to [Node.js' `dns.lookup()`](https://nodejs.org/api/dns.html#dns_dns_lookup_hostname_options_callback) function. May be either `0`, `4`, or `6`. `4` means use IPv4 only, `6` means use IPv6 only, `0` means try both.
 * @param {boolean} [options.autoCreate=false] Set to `true` to make Mongoose automatically call `createCollection()` on every model created on this connection.
 * @see Mongoose#createConnection https://mongoosejs.com/docs/api/mongoose.html#Mongoose.prototype.createConnection()
 * @api public
 * @return {Promise} resolves to `this` if connection succeeded
 */

Mongoose.prototype.connect = async function connect(uri, options) {
  if (typeof options === 'function' || (arguments.length >= 3 && typeof arguments[2] === 'function')) {
    throw new MongooseError('Mongoose.prototype.connect() no longer accepts a callback');
  }

  const _mongoose = this instanceof Mongoose ? this : mongoose;
  if (_mongoose.connection == null) {
    _createDefaultConnection(_mongoose);
  }
  const conn = _mongoose.connection;

  return conn.openUri(uri, options).then(() => _mongoose);
};

/**
 * Runs `.close()` on all connections in parallel.
 *
 * @return {Promise} resolves when all connections are closed, or rejects with the first error that occurred.
 * @api public
 */

View on GitHub (pinned to 49cdab0136)

When it happens

Trigger: Thrown at lib/mongoose.js:466 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Automattic/mongoose@49cdab0136 (2026-08-21). Data as JSON: /api/errors/a9c871d0802f49f3. Report an issue: GitHub.