HTTP 505 — HTTP Version Not Supported

The server does not support the HTTP protocol version used in the request

When to use it

Use status 505 when this is the correct HTTP response semantic: The server does not support the HTTP protocol version used in the request

Request and response example

GET /service HTTP/1.1
Host: api.example.com

HTTP/1.1 505 HTTP Version Not Supported
Content-Type: application/json

{"error":"Service failed to process the request"}

Related status codes

500, 501, 502, 503

References

MDN · RFC 9110