Automattic/mongoose · error · MongooseError

Cannot overwrite Schema.indexTypes

Error message

Cannot overwrite Schema.indexTypes

What it means

Schema.indexTypes is a read-only static listing the valid index types ('2d', '2dsphere', 'hashed', 'text'); mongoose installs a getter with a throwing setter so this lookup table cannot be silently replaced. Any assignment to the property raises this error.

Source

Thrown at lib/schema.js:2531

};

const indexTypes = '2d 2dsphere hashed text'.split(' ');

/**
 * The allowed index types
 *
 * @property {string[]} indexTypes
 * @memberOf Schema
 * @static
 * @api public
 */

Object.defineProperty(Schema, 'indexTypes', {
  get: function() {
    return indexTypes;
  },
  set: function() {
    throw new MongooseError('Cannot overwrite Schema.indexTypes');
  }
});

/**
 * Returns a list of indexes that this schema declares, via `schema.index()` or by `index: true` in a path's options.
 * Indexes are expressed as an array `[spec, options]`.
 *
 * #### Example:
 *
 *     const userSchema = new Schema({
 *       email: { type: String, required: true, unique: true },
 *       registeredAt: { type: Date, index: true }
 *     });
 *
 *     // [ [ { email: 1 }, { unique: true } ],
 *     //   [ { registeredAt: 1 }, {} ] ]
 *     userSchema.indexes();
 *

View on GitHub (pinned to 49cdab0136)

Solutions

1. Delete the assignment - indexTypes is informational and not user-configurable.
2. Create exotic indexes directly on the collection with the driver (collection.createIndex) instead.
3. Audit Object.assign/extend calls targeting Schema and skip read-only statics (getter without setter).

Example fix

// before
mongoose.Schema.indexTypes = ['2d', '2dsphere', 'myIndexType'];

// after
schema.index({ loc: '2dsphere' }); // declare supported index types per-path
await model.collection.createIndex({ a: 1 }, { unique: true }); // exotic options go to the driver

const safeAssignStatics = (target, source) => {
  for (const k of Object.keys(source)) {
    const d = Object.getOwnPropertyDescriptor(target, k);
    if (d && d.get && !d.set) continue; // skip read-only statics like indexTypes
    target[k] = source[k];
  }
};

When it happens

Trigger: A direct write such as `mongoose.Schema.indexTypes = [...]`; helper code that copies statics via Object.assign(Schema, src); monkey-patching or test stubbing that treats class statics as writable.

Common situations: Attempting to extend the allowed index types (not supported - index types come from the server/driver); generic merge/extend utilities applied to the Schema class; migration scripts that clone mongoose internals.

AI-assisted analysis of Automattic/mongoose@49cdab0136 (2026-08-21). Data as JSON: /api/errors/165a3cb1904bacc0. Report an issue: GitHub.