httpstatuses/contents/codes/411.md

set	code	title	references
4	411	Length Required	Rails HTTP Status Symbol :length_required

The 411 (Length Required) status code indicates that the server refuses to accept the request without a defined Content-Length (Section 3.3.2 of RFC7230). The client MAY repeat the request if it adds a valid Content-Length header field containing the length of the message body in the request message.

Source: RFC7231 Section 6.5.10