505 HTTP Version Not Supported
This is an educational reference page about HTTP 505 HTTP Version Not Supported. The page itself is served as 200 OK so it can be indexed as HTTP documentation.
The server does not support the HTTP protocol version used in the request.
Specification
Registered in the IANA HTTP Status Code Registry as HTTP Version Not Supported. Defined in RFC 9110, Section 15.6.6.
Header and content rules
What RFC 9110 says about a 505 response, quoted from the RFC. The 5xx class rules also apply.
- SHOULD (server; content): Explain why the HTTP version is not supported and which protocols are. Table row
The server SHOULD generate a representation for the 505 response that describes why that version is not supported and what other protocols are supported by that server. RFC 9110 §15.6.6
The same rule is in the response obligations table and its JSON.