Automattic/mongoose · warning · MongooseError

No connections to database "${name}" found

Error message

No connections to database "${name}" found

What it means

Connection.prototype.removeDb(name) closes and detaches databases previously created on that connection via useDb(). It throws a MongooseError when no tracked db with that name exists in conn.otherDbs - the name was never created with useDb() on this connection, was already removed, or belongs to a different connection object.

Source

Thrown at lib/drivers/node-mongodb-native/connection.js:169

 *     // Connect to `initialdb` first
 *     const conn = await mongoose.createConnection('mongodb://127.0.0.1:27017/initialdb').asPromise();
 *
 *     // Creates an un-cached connection to `mydb`
 *     const db = conn.useDb('mydb');
 *
 *     // Closes `db`, and removes `db` from `conn.relatedDbs` and `conn.otherDbs`
 *     await conn.removeDb('mydb');
 *
 * @method removeDb
 * @memberOf Connection
 * @param {string} name The database name
 * @return {Connection} this
 */

NativeConnection.prototype.removeDb = function removeDb(name) {
  const dbs = this.otherDbs.filter(db => db.name === name);
  if (!dbs.length) {
    throw new MongooseError(`No connections to database "${name}" found`);
  }

  for (const db of dbs) {
    db._closeCalled = true;
    db._destroyCalled = true;
    db._readyState = STATES.disconnected;
    db.$wasForceClosed = true;
  }
  delete this.relatedDbs[name];
  this.otherDbs = this.otherDbs.filter(db => db.name !== name);
};

/**
 * Closes the connection
 *
 * @param {boolean} [force]
 * @return {Connection} this
 * @api private

View on GitHub (pinned to 49cdab0136)

Solutions

1. Check existence first: if (conn.relatedDbs['tenant42']) conn.removeDb('tenant42') - relatedDbs keys are the db names.
2. Ensure the db was created from the same connection instance: const db = conn.useDb(name).
3. Track removed tenants in your lifecycle code to avoid double removal.

Example fix

// before
conn.removeDb('tenant42'); // throws if not created on this connection

// after
if (conn.relatedDbs['tenant42'] != null) {
  conn.removeDb('tenant42');
}

function removeDbSafe(conn, name) {
  if (!Object.prototype.hasOwnProperty.call(conn.relatedDbs, name)) {
    return false; // nothing to remove
  }
  conn.removeDb(name);
  return true;
}

function hasDb(conn, name) {
  return conn.relatedDbs[name] != null;
}

When it happens

Trigger: conn.removeDb('tenantDb') where 'tenantDb' was created via a different connection (e.g. mongoose.connection vs a createConnection() instance); calling removeDb twice for the same name; a typo in the database name.

Common situations: Multi-tenant code that creates per-tenant dbs with useDb() and cleans them up on logout; shutdown cleanup racing another cleanup that already removed the db; tests iterating over created dbs.

Related errors

• Connection#createClient not implemented by driver
• Cannot call `${this.name}.${i}()` before initial connection
• Connection has been closed and destroyed, and cannot be used
• `useConnection()` requires a Mongoose connection.
• The connection passed to `useConnection()` has a different v

AI-assisted analysis of Automattic/mongoose@49cdab0136 (2026-08-21). Data as JSON: /api/errors/32d0e0712eb04186. Report an issue: GitHub.