AMP Page URL loops
This means that the URL in question contains an <amphtml> tag pointing at a URL, where this URL also has <amphtml> tag, that points back at the original URL.
Why is this important?
This setup would be the result of a misconfiguration, and the AMP Page would actually not be discoverable, since the AMP links loop back on themselves. If AMP URLs are not discoverable via crawling, search engines may fail to index the AMP Page or show it in search results.
What does the Hint check?
This Hint will trigger for any internal URL which references an AMP Page, which contains an <amphtml> tag that references the original URL.
Examples that trigger this Hint
Consider the URL: https://example.com/page-a/
The Hint would trigger for this URL if it included a <link> tag that referenced a URL as an AMP page:
where this URL includes a <link> tag referencing the original page as an AMP page:
How do you resolve this issue?
Often, a site is set up with both AMP and non-AMP pages. It is important that search engines are able to discover both types of page while crawling, and that each page is internally consistent in how they reference one another.
In this case, the <amphtml> tag is pointing to completely the wrong URL, so you will either need to manually update this, or update the script that powers it.
To set discoverability up correctly, the configuration should look like this:
For the URL: https://example.com/page-a/
This page defines a self-reference canonical and an AMP page:
Then the AMP page has a canonical pointing back at https://example.com/page-a/