Front desk · HTTP Status Codes
4×× Client Error
431 Request Header Fields Too Large
· filed 2026-07-18 · click a code to copy
HTTP 431 Request Header Fields Too Large is a client error-class status code defined in RFC6585. Request header fields are too large for the server to process.
Client-error responses signal that the problem is on the requesting side: the request is malformed, unauthorized, or aimed at something that isn't there. On the wire, the response begins with the status line HTTP/1.1 431 Request Header Fields Too Large.