HTTP 411 – Length Required
The server refuses to accept the request without a defined Content-Length header.
Common use case
Returned by servers that reject chunked or streamed uploads where the exact body size isn't known in advance.
Example
HTTP/1.1 411 Length Required
History
Part of the original HTTP/1.1 spec, RFC 2068 (1997).
Did you know?
Modern HTTP/1.1 clients almost always set Content-Length automatically, so this code is now rarely triggered outside of hand-rolled HTTP requests.