505
HTTP Version Not Supported
5xx Server error
Class
RFC 9110 §15.6.6
Defined in
What does HTTP 505 mean?
The server does not support the HTTP version used in the request. Rare today; it can appear with very old servers or when a client sends a malformed request line.
5xx Server error: The request looked valid, but the server failed to fulfil it. The fix is on the server side.
505 and SEO
Rare; pages returning 505 are not indexed.
Example response
HTTP/1.1 505 HTTP Version Not SupportedRelated status codes
- 400 Bad Request — The server cannot process the request because it is malformed.
- 426 Upgrade Required — The server requires the client to switch to a different protocol.
Check which status code a URL returns with the HTTP header checker.
All HTTP status codesSearch the full list of status codes from 100 to 599 with their meanings and SEO impact.
Open the full list Frequently asked questions
What does status code 505 mean?
505 HTTP Version Not Supported: The server does not support the HTTP version used in the request.
Does 505 affect SEO?
Rare; pages returning 505 are not indexed.