define-validation-error-response

Requires every operation to define 400, 422, or the 4XX range response.

Attribute	Value
Category	Operations
Maturity	Platinum
OpenAPI	Swagger 2.0; OpenAPI 3.0, 3.1, 3.2
Starter	Off
Lenient–Strict	Warning
Complete	Error

Intent

Clients need a documented outcome for requests rejected because their input is invalid.

Flags

An operation whose response keys contain none of exactly 400, 422, or 4XX.

Does not flag

An operation defining any one of those keys. This rule checks only response presence, not whether it contains a body or schema.

See it fail

responses:
  '201':
    description: Created

Diagnostic: Operations should define one of `400`, `422`, or `4XX` responses.

Fix it

Choose the status used by the API and document it:

responses:
  '422':
    description: Validation failed
    content:
      application/problem+json:
        schema:
          $ref: '#/components/schemas/Problem'

Configure

profiles:
  default:
    rules:
      extends: [recommended]
      override:
        define-validation-error-response: error

Nearby: operation-4xx-problem-details-rfc7807, error-response-media-type.