431 Request Header Fields Too Large

The server is unwilling to process the request because its header fields are too large. The request MAY be resubmitted after reducing the size of the request header fields.

It can be used when the total set of request header fields is too large, or when a single header field is at fault. In the latter case, the response representation SHOULD specify which header field was too large. For example:

HTTP/1.1 431 Request Header Fields Too Large
Content-Type: text/html


 Request Header Fields Too Large


 Request Header Fields Too Large
 The "Example" header was too large.

Responses with the 431 status code MUST NOT be stored by a cache.