Server error · HTTP reference

505HTTP Version Not Supported

The server does not support this HTTP protocol version.

The company behind the code.

For protocol testing and server modernisation.

505HTTP Version Not Supported

The server does not support this HTTP protocol version.

Available

For protocol testing and server modernisation.

Your logo, your message, your corner of the internet.

Try the response.

Returns this HTTP status with the current sponsor’s name, advertising message and website. Useful for testing how your app handles a response.

GET /responses/505Open response RFC 9110, section 15.6.6

This is an independent project. Sponsorship does not confer ownership of HTTP standards.

Understanding 5xx responses.

Server error responses describe failures in the server or its upstream services.

Inspect server and gateway logs, and check service availability. Retrying requests that change data can duplicate an operation unless the API supports safe retries.

Reference reviewed 5 September 2026. How we use sources.

Related status codes.

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