417 Expectation Failed
This is an educational reference page about HTTP 417 Expectation Failed. The page itself is served as 200 OK so it can be indexed as HTTP documentation.
The server cannot meet the requirements of the Expect request-header field.
Specification
Registered in the IANA HTTP Status Code Registry as Expectation Failed. Defined in RFC 9110, Section 15.5.18.
Header and content rules
RFC 9110 adds no header or content rule specific to 417. The 4xx class rules also apply. See 417 in the response obligations table.