HTTP 417 – Expectation Failed
The expectation given in the Expect request header could not be met.
Common use case
Returned when a server doesn't support the "Expect: 100-continue" mechanism a client is relying on before sending a large body.
Example
HTTP/1.1 417 Expectation Failed
History
Part of the original HTTP/1.1 spec, RFC 2068 (1997).
Did you know?
It is a direct counterpart to 100 Continue - one confirms the expectation can be met, the other confirms it can't.