HTTP 505 HTTP Version Not Supported

Server Error

The server does not support the HTTP protocol version used in the request.

Common Causes

Client using an unsupported HTTP version
Misconfigured client sending HTTP/3 to an HTTP/1.1-only server

How to Fix

Use a supported HTTP version (typically HTTP/1.1 or HTTP/2)
Update server software to support newer HTTP versions

Related Status Codes

400 Bad Request 501 Not Implemented

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