510 Not Extended

What is HTTP 510?

This status code indicates that the server requires further extensions to the request before it can process it. The client's request is missing an extension that the server needs in order to fulfill it. The server should provide information about what extensions are required in the response. This code is rarely seen in practice, as the HTTP Extension Framework it was designed for has limited adoption.

Defined in RFC 2774

Common Causes

• The server requires an HTTP extension that was not included in the request
• A mandatory extension declared by the server is not supported by the client
• The request lacks required extension-specific headers for processing

How to Fix

• Check the response for details on which extension the server requires
• Add the required extension headers to your request and retry
• Verify that your HTTP client supports the extensions the server mandates