Automattic/mongoose · error · MongooseError

Cannot set nested path `${path}`. Parent path `${fullPath}`

Error message

Cannot set nested path `${path}`. Parent path `${fullPath}` already set to type ${branch[sub].name}.

What it means

Error "Cannot set nested path `${path}`. Parent path `${fullPath}` already set to type ${branch[sub].name}." thrown in Automattic/mongoose.

Source

Thrown at lib/schema.js:1342

  let branch = this.tree;
  let fullPath = '';

  for (const sub of subpaths) {
    if (utils.specialProperties.has(sub)) {
      throw new MongooseError('Cannot set special property `' + sub + '` on a schema');
    }
    fullPath = fullPath += (fullPath.length > 0 ? '.' : '') + sub;
    if (!branch[sub]) {
      this.nested[fullPath] = true;
      branch[sub] = {};
    }
    if (typeof branch[sub] !== 'object') {
      const msg = 'Cannot set nested path `' + path + '`. '
          + 'Parent path `'
          + fullPath
          + '` already set to type ' + branch[sub].name
          + '.';
      throw new MongooseError(msg);
    }
    branch = branch[sub];
  }

  branch[last] = clone(obj);

  this.paths[path] = this.interpretAsType(path, obj, this.options);
  const schemaType = this.paths[path];

  // If overwriting an existing path, make sure to clear the childSchemas
  this.childSchemas = this.childSchemas.filter(childSchema => childSchema.path !== path);

  if (schemaType.$isSchemaMap) {
    // Maps can have arbitrary keys, so `$*` is internal shorthand for "any key"
    // The '$' is to imply this path should never be stored in MongoDB so we
    // can easily build a regexp out of this path, and '*' to imply "any key."
    const mapPath = path + '.$*';

View on GitHub (pinned to 49cdab0136)

When it happens

Trigger: Thrown at lib/schema.js:1342 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/83fb3063a40c853c. Report an issue: GitHub.