505 HTTP Version Not Supported

The HTTP505 HTTP Version Not Supportedserver error responsestatus code indicates that the HTTP version used in the request is not supported by the server.

It's common to see this error when a request line is improperly formed such asGET /path to resource HTTP/1.1or with\nterminating the request line instead of\r\n. For example, intermediaries such as load balancers may not handle request lines of a forwarded request as illustrated in the example below.

Status

http
505 HTTP Version Not Supported

Specifications

Specification
HTTP Semantics
#status.505

Examples

A 505 due to malformed request-line

In the following example, a client requestsexample /dog%20trainers,but due to incorrect load balancer configuration, thepercent encodingin the URL is not handled properly. In this case, the origin server seestrainersinstead of the HTTP version, and a505response is returned instead. A request identifier is contained in the response body for illustration of a way that may help server administrators narrow down the root cause of the problem:

http
GET /dog trainers HTTP/1.1
Host: example
http
HTTP/1.1 505 HTTP Version Not Supported
Content-Type: text/html;
Content-Length: 123

<!doctype html>
<html lang= "en" >
<head>
<title>505 HTTP Version Not Supported</title>
</head>
<body>
<h1>505 HTTP Version Not Supported</h1>
<p>If this problem persists, please <a href= "https://example /support" >contact support</a>.</p>
<p>Server logs contain details of this error with request ID: ABC-123.</p>
</body>
</html>

See also