HTTP 510 Not Extended means the request requires additional extensions to the HTTP protocol that the server does not support. The client must include the required extension declarations in the request.
Status
510 Not ExtendedExample
Request
GET /page HTTP/1.1
Host: www.example.com
User-Agent: Mozilla/5.0
Accept: text/htmlResponse
HTTP/1.1 510 Not Extended
Content-Type: text/html; charset=utf-8
Content-Length: 200
<!doctype html>
<html lang="en">
<head>
<title>510 Not Extended</title>
</head>
<body>
<h1>Not Extended</h1>
<p>The server requires an extension to process your request that was not included.</p>
</body>
</html>How to Troubleshoot
1
Check required extensions
The response body should specify which extensions are required.
2
Include the required extension headers
Add the necessary extension headers to your request as specified by the server.
Common Causes
Missing HTTP extension
highThe server requires an HTTP extension that the client did not include in the request.
Related Status Codes
References
| Specification | Section |
|---|---|
| An HTTP Extension Framework | RFC 2774 §7 |
Frequently Asked Questions
This reference was compiled from official RFCs, protocol specifications, and hands-on troubleshooting experience. AI tools were used primarily for formatting and organizing the content on the page.