AMP Page URL loops
This means that the URL in question defines an AMP Page URL, where the <amphtml> tag points back at the original URL.
Why is this important?
This setup would be the result of a misconfiguration, as the AMP Page would actually not be discoverable, since it is not referenced. 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, where the <amphtml> tag references the same 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 itself 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/