HTTP 494 – Request Header Too Large
(NGINX) The request header sent by the client is larger than the buffer the server is configured to accept.
Common use case
Seen when NGINX's large_client_header_buffers setting is too small for an oversized cookie, referer, or authorization header.
History
An NGINX-specific extension distinct from the standard 431 code, predating that RFC.
Did you know?
It predates the official 431 status code by years - NGINX had already invented its own answer to the same problem before the IETF standardised one.