HTTP 505 HTTP Version Not Supported

In short: The server does not support the HTTP version of the request.

In more detail: Rare: a client speaks a version (e.g. HTTP/2 or HTTP/0.9) the server does not know. Modern browsers negotiate the version and fall back to HTTP/1.1 if needed.

In Depth

When it occurs

• Very old or very new clients facing an unusually configured server.
• Faulty proxies or tools that send wrong version information.

What you can do

1. Try another browser or client.
2. Operators: keep HTTP/1.1 enabled, which all clients understand.

See also: HTTP Status Codes Overview, HTTP