HTTP status codes / 5xx — Server errors
505 HTTP Version Not Supported
The server refuses the HTTP version of the request.
What it means
The protocol version in the request line is not supported. Practically extinct, occasionally produced by ancient servers or hand-crafted requests.
Common causes
- Hand-crafted request with a bogus HTTP version
- Museum-grade server software
How to debug it
Force HTTP/1.1 in your client and retry.
Server-side note: Force HTTP/1.1 in the client.
The fastest way to pin down a 505 is to reproduce the exact request and inspect what actually went over the wire — status, headers, timing and body, without your app code in the way. That is what an API client is for; ReqPad does it from your phone, with every request saved to history.
Related codes
500 Internal Server Error · 501 Not Implemented · 502 Bad Gateway · 503 Service Unavailable · 504 Gateway Timeout · 506 Variant Also Negotiates — or the full reference.
Reproduce that 505 in 10 seconds.
Build the request, send it, read status + headers + timing — on your iPhone. Free to start.