mongodb/node-mongodb-native · error · MongoParseError

Option pkFactory must be an object with a createPk function,

Error message

Option pkFactory must be an object with a createPk function, got ${value}

What it means

`pkFactory` overrides how `_id` values are generated and must be an object exposing a `createPk` function. The transform (src/connection_string.ts:952-961) requires `isRecord(value, ['createPk'])` AND `typeof value.createPk === 'function'`; otherwise it throws.

Source

Thrown at src/connection_string.ts:958

    type: 'boolean'
  },
  name: {
    target: 'driverInfo',
    transform({ values: [value], options }) {
      return { ...options.driverInfo, name: String(value) };
    }
  } as OptionDescriptor,
  noDelay: {
    default: true,
    type: 'boolean'
  },
  pkFactory: {
    default: DEFAULT_PK_FACTORY,
    transform({ values: [value] }): PkFactory {
      if (isRecord(value, ['createPk'] as const) && typeof value.createPk === 'function') {
        return value as PkFactory;
      }
      throw new MongoParseError(
        `Option pkFactory must be an object with a createPk function, got ${value}`
      );
    }
  },
  promoteBuffers: {
    type: 'boolean'
  },
  promoteLongs: {
    type: 'boolean'
  },
  promoteValues: {
    type: 'boolean'
  },
  useBigInt64: {
    type: 'boolean'
  },
  proxyHost: {
    type: 'string'

View on GitHub (pinned to 3366c21a63)

Solutions

1. Provide `{ createPk: () => /* ObjectId or value */ }`
2. Omit pkFactory to use the default ObjectId factory
3. Ensure createPk is a function, not a method-name string

Example fix

// before
new MongoClient(uri, { pkFactory: () => new ObjectId() });
// after
new MongoClient(uri, { pkFactory: { createPk: () => new ObjectId() } });

function isValidPkFactory(v) {
  return v != null && typeof v === 'object' && typeof v.createPk === 'function';
}
if (options.pkFactory && !isValidPkFactory(options.pkFactory)) {
  throw new TypeError('pkFactory must be { createPk: () => any }');
}

function isPkFactory(v) {
  return !!v && typeof v === 'object' && typeof v.createPk === 'function';
}

When it happens

Trigger: `{ pkFactory: {} }` (no createPk); `{ pkFactory: { createPk: 'x' } }` (not a function); `{ pkFactory: () => new ObjectId() }` (function instead of object); `{ pkFactory: null }`.

Common situations: Migrating from an older driver where a function was accepted; partial implementation of a custom factory; forgetting to wrap the function in an object.

Related errors

• Descriptors missing a type must define a transform
• ${name} must be an object with 'username' and 'password' pro
• authMechanism one of ${mechanisms}, got ${value}
• Invalid `serverApi` property; must specify a version from th
• Invalid server API version=${versionToValidate}; must be in

AI-assisted analysis of mongodb/node-mongodb-native@3366c21a63 (2026-08-04). Data as JSON: /data/errors/49a9665946f7c63e.json. Report an issue: GitHub.