The HTTP 428 Precondition Required response status code indicates that the server requires the request to be conditional.
Typically, this means that a required precondition header, such as If-Match, is missing.
When a precondition header is not matching the server side state, the response should be 412 Precondition Failed.
Status
428 Precondition Required
Specifications
| Specification | Title |
|---|---|
| RFC 6585, section 3: 428 Precondition Required | Additional HTTP Status Codes |