HTTP resource not retrievable. The HTTP status from the remote server was: 508.

A remote resource referenced in your HTML returned an HTTP 508 (Loop Detected) status, meaning the server encountered an infinite loop while trying to serve the file.

This error occurs when your HTML references an external resource — such as a stylesheet, script, image, or other linked file — and the server hosting that resource gets stuck in a redirect loop or circular dependency. The W3C validator tried to fetch the resource but couldn't because the remote server gave up.

This is a server-side issue, not an HTML syntax error. The problem lies with the server hosting the resource, not your markup. Common causes include misconfigured redirects, circular symbolic links on the server, or WebDAV configurations that detect infinite loops.

To fix this, you should:

1. Check the URL — Open the referenced URL directly in a browser to confirm it fails.
2. Fix the server configuration — If you control the server, look for circular redirects or recursive includes.
3. Host the resource yourself — If you don't control the remote server, download the resource and serve it locally.
4. Use a different CDN or source — Switch to a reliable alternative host.

HTML Examples

Before: referencing an unreachable remote resource

<link rel="stylesheet" href="https://example.com/looping/styles.css">
<script src="https://example.com/looping/app.js"></script>

After: hosting locally or using a reliable CDN

<link rel="stylesheet" href="/css/styles.css">
<script src="/js/app.js"></script>

If the resource is a popular library, use a trusted CDN instead:

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css">

Learn more:

MDN Reference

HTTP status codes - MDN Web Docs

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