// REFERENCE
431 Request Header Fields Too Large
Class: 4xx
The headers (often huge cookies or many Referers) exceed the server limit. Shrink cookie size or clean up headers.
Related tools
Work with this in:
Related
400
400 Bad Request 401
401 Unauthorized (not authenticated) 403
403 Forbidden (access denied) 404
404 Not Found 405
405 Method Not Allowed 406
406 Not Acceptable
400 Bad Request 401
401 Unauthorized (not authenticated) 403
403 Forbidden (access denied) 404
404 Not Found 405
405 Method Not Allowed 406
406 Not Acceptable
Semantics per RFC 9110 and the IANA status code registry. Educational content.