The server does not support the HTTP protocol version used in the request.
Quick facts
When does it occur
The server does not support the HTTP protocol version used in the request.
It belongs to the 5xx Server Error class of responses, defined in RFC7231#6.6.6.
Browse all codes in this class: 5xx Server Error
Common causes
Frequently asked questions
505 belongs to the 5xx Server Error class and is generally not cached for long; behavior is controlled by Cache-Control.
5xx Server Error: The server does not support the HTTP protocol version used in the request.
Sources & standards
Updated 2026-08-18
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