Automattic/mongoose · error · TypeError

utils.populate: invalid path. Expected string or array of st

Error message

utils.populate: invalid path. Expected string or array of strings. Got typeof `${typeof path}`

What it means

Error "utils.populate: invalid path. Expected string or array of strings. Got typeof `${typeof path}`" thrown in Automattic/mongoose.

Source

Thrown at lib/utils.js:597

      select: select,
      match: model,
      options: match
    };
  } else {
    obj = {
      path: path,
      select: select,
      model: model,
      match: match,
      options: options,
      populate: subPopulate,
      justOne: justOne,
      count: count
    };
  }

  if (typeof obj.path !== 'string' && !(Array.isArray(obj.path) && obj.path.every(el => typeof el === 'string'))) {
    throw new TypeError('utils.populate: invalid path. Expected string or array of strings. Got typeof `' + typeof path + '`');
  }

  return _populateObj(obj);

  // The order of select/conditions args is opposite Model.find but
  // necessary to keep backward compatibility (select could be
  // an array, string, or object literal).
  function makeSingles(arr) {
    const ret = [];
    arr.forEach(function(obj) {
      if (oneSpaceRE.test(obj.path)) {
        const paths = obj.path.split(manySpaceRE);
        paths.forEach(function(p) {
          const copy = Object.assign({}, obj);
          copy.path = p;
          ret.push(copy);
        });
      } else {

View on GitHub (pinned to 49cdab0136)

When it happens

Trigger: Thrown at lib/utils.js:597 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/ff037269f227cdb1. Report an issue: GitHub.