431
Request Header Fields Too Large
Client errors (4xx)·RFC 6585
What 431 means
The server refuses the request because its header fields are too large.
Often caused by an oversized Cookie header; clear cookies or reduce header size.
Client errors (4xx)
The request contains an error from the client — bad syntax, missing auth or a wrong URL.
Other 4xx codes
400Bad Request401Unauthorized402Payment Required403Forbidden404Not Found405Method Not Allowed406Not Acceptable407Proxy Authentication Required408Request Timeout409Conflict410Gone411Length Required412Precondition Failed413Content Too Large414URI Too Long415Unsupported Media Type416Range Not Satisfiable417Expectation Failed418I'm a teapot421Misdirected Request422Unprocessable Content423Locked424Failed Dependency425Too Early426Upgrade Required428Precondition Required429Too Many Requests451Unavailable For Legal Reasons
FAQ — 431
What does HTTP 431 mean?
431 Request Header Fields Too Large: The server refuses the request because its header fields are too large. Often caused by an oversized Cookie header; clear cookies or reduce header size.
Which class does status code 431 belong to?
431 is a Client errors (4xx) code. The request contains an error from the client — bad syntax, missing auth or a wrong URL.
Where is the 431 code defined?
Status code 431 is defined in RFC 6585 and is part of the IANA HTTP Status Code Registry.