5xx Server error

505 HTTP Version Not Supported

The server doesn't support the HTTP version used.

What 505 means

Rare: the client used an HTTP version the server rejects.

Common causes

A very old or very new HTTP version, or a misconfigured client.

How to fix it

If you're calling an API

Use HTTP/1.1 (curl --http1.1).

If you run the server

Support HTTP/1.1 at minimum.

Should you retry?

With a supported version.

Example response

HTTP

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

{
  "type": "about:blank",
  "title": "HTTP Version Not Supported",
  "status": 505,
  "detail": "The server doesn't support the HTTP version used."
}

Defined in: RFC 9110 (HTTP Semantics). 505 is a server error: the problem is on the server's side.

Debugging an API call? Convert your request with the cURL converter, check the response with the JSON formatter, or see whether the API is down on its status page.

HTTP 505 FAQ

What does HTTP 505 mean?

505 HTTP Version Not Supported: The server doesn't support the HTTP version used. Rare: the client used an HTTP version the server rejects.

Is 505 a client or server error?

It's a server error (5xx): the server failed to handle a valid request, so the fix is usually on the server's side.

How do I fix a 505 error?

Use HTTP/1.1 (curl --http1.1).

Should I retry after a 505?

With a supported version.

Other 5xx status codes

All HTTP status codes