Automattic/mongoose · error · Error

Discriminator "${name}" cannot have field with name "${key}"

Error message

Discriminator "${name}" cannot have field with name "${key}"

What it means

Error "Discriminator "${name}" cannot have field with name "${key}"" thrown in Automattic/mongoose.

Source

Thrown at lib/helpers/model/discriminator.js:120

    existingPath.options.$skipDiscriminatorCheck = true;
  } else {
    const baseSchemaAddition = {};
    baseSchemaAddition[key] = {
      default: void 0,
      select: true,
      $skipDiscriminatorCheck: true
    };
    baseSchemaAddition[key][model.schema.options.typeKey] = String;
    model.schema.add(baseSchemaAddition);
    defineKey({
      prop: key,
      prototype: model.prototype,
      options: model.schema.options
    });
  }

  if (schema.path(key) && schema.path(key).options.$skipDiscriminatorCheck !== true) {
    throw new Error('Discriminator "' + name +
        '" cannot have field with name "' + key + '"');
  }

  let value = name;
  if ((typeof tiedValue === 'string' && tiedValue.length) || tiedValue != null) {
    value = tiedValue;
  }

  validateDiscriminatorSchemasForEncryption(model.schema, schema);

  function merge(schema, baseSchema) {
    // Retain original schema before merging base schema
    schema._baseSchema = baseSchema;
    if (baseSchema.paths._id &&
        baseSchema.paths._id.options &&
        !baseSchema.paths._id.options.auto) {
      schema.remove('_id');
    }

View on GitHub (pinned to 49cdab0136)

When it happens

Trigger: Thrown at lib/helpers/model/discriminator.js:120 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/e3add2a2fc154641. Report an issue: GitHub.