Error AtlasError Documentation and Resolution
Back to search

HTTP Status Codes

HTTP 505 HTTP Version Not Supported

505 HTTP Version Not Supported

The server does not support, or refuses to support, the major HTTP version used in the request message.

505 HTTP Version Not Supportedgeneral

Observed message

505 HTTP Version Not Supported

Why it happens

  • The client is sending an HTTP version the server does not support.
  • A proxy, library, or custom client forced an incompatible protocol version.
  • The server's protocol handling or upgrade path is misconfigured.

How to fix it

  1. Check which HTTP versions the target server or API actually supports.
  2. Update the client or library configuration to use a supported HTTP version.
  3. Review reverse proxies or protocol gateways that may be rewriting or blocking the expected version.

Official reference

MDN: 505 HTTP Version Not Supported

Related errors

400 Bad RequestHTTP 400 Bad Request404 Not FoundHTTP 404 Not Found406 Not AcceptableHTTP 406 Not Acceptable410 GoneHTTP 410 Gone

Explore more

generalBrowse more general errors
505 HTTP Version Not Supported: what it means and how to fix it | Error Atlas