status Registered
Verified 2026-09-18 · registry updated
2025-09-15HTTP 428 Precondition Required
The server requires the request to be conditional.
Use 428 to prevent lost updates by requiring a validator such as If-Match.
httpstatus codeconditionalconcurrency
Response (http)
HTTP/1.1 428 Precondition Required
Use 428 to prevent lost updates by requiring a validator such as If-Match.
Common mistakes
- Enforcing required preconditions only intermittently; inconsistent enforcement defeats lost-update protection.
Registry reference: rfc6585