medusajs/medusa · error · MedusaError

Rule attribute must be a string

Error message

Rule attribute must be a string

What it means

Within validateRule, the rule's attribute must be a string. Passing a number, object, or symbol as attribute throws INVALID_DATA.

Source

Thrown at packages/modules/fulfillment/src/utils/utils.ts:107

  }

  return loopComparator.apply(rules, [predicate])
}

/**
 * Validate contextValue rule object
 * @param rule
 */
export function validateRule(rule: Record<string, unknown>): boolean {
  if (!rule.attribute || !rule.operator || !rule.value) {
    throw new MedusaError(
      MedusaError.Types.INVALID_DATA,
      "Rule must have an attribute, an operator and a value"
    )
  }

  if (!isString(rule.attribute)) {
    throw new MedusaError(
      MedusaError.Types.INVALID_DATA,
      "Rule attribute must be a string"
    )
  }

  if (!isString(rule.operator)) {
    throw new MedusaError(
      MedusaError.Types.INVALID_DATA,
      "Rule operator must be a string"
    )
  }

  if (!availableOperators.includes(rule.operator as RuleOperator)) {
    throw new MedusaError(
      MedusaError.Types.INVALID_DATA,
      `Rule operator ${
        rule.operator
      } is not supported. Must be one of ${availableOperators.join(", ")}`

View on GitHub (pinned to 5e06e544a2)

Solutions

1. Coerce/validate attribute to a string before calling the service
2. Use known attribute identifiers as string constants

Example fix

// before
rules: [{ attribute: 42, operator: 'eq', value: 'x' }]
// after
rules: [{ attribute: String(42), operator: 'eq', value: 'x' }])

const hasStringAttribute = (r: any): boolean => typeof r?.attribute === 'string' && r.attribute.length > 0

When it happens

Trigger: Programmatically building rules with computed keys or unserialized values, e.g. { attribute: 123, ... } or attribute taken from untyped JSON input.

Common situations: CSV/external imports mapping columns to attributes without coercing to string; client sending numeric attribute identifiers.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Rule operator must be a string
• The following rules does not exists: ${Array.from(nonAlready
• Rule must have an attribute, an operator and a value
• Rule operator ${rule.operator} is not supported. Must be one
• Rule value must be an array for in/nin operators

AI-assisted analysis of medusajs/medusa@5e06e544a2 (2026-08-27). Data as JSON: /api/errors/bea602fb97fa2a17. Report an issue: GitHub.