What this signifies is a situation where an AMP HTML tag (<amphtml>) in a URL is directing to another URL, and this second URL contains an AMP HTML tag that links back to the first one.
Why is this important?
This type of configuration is indicative of a setup error. It prevents the AMP Page from being accessible as the linking becomes cyclic. A lack of discoverability by search engine crawlers can result in non-indexing of the AMP Page or it being omitted from search results.
What does the Optimization check?
The Optimization will be activated for any internal URL which points to an AMP Page, which includes an <amphtml> tag that points back to the initiating URL.
Examples that trigger this Optimization
Take for instance the URL: https://example.com/page-a/
This Optimization would be activated if this URL included a <link> tag relating to a distinct AMP URL:
<link rel="amphtml" href="https://example.com/page-b/">
And if "page-b" contains a <link> tag that references back to "page-a" as an AMP page:
<link rel="amphtml" href="https://example.com/page-a/">
How do you resolve this issue?
Correctly setting up a website typically involves both AMP and non-AMP pages and it is crucial for search engines to uncover both when crawling. Each page type should internally reference the other correctly.
In this scenario, an erroneous <amphtml> tag directs to an incorrect URL and must therefore be rectified either manually or through a script update that handles it.
The correct configuration should be as follows:
For the URL: https://example.com/page-a/
This page should have a canonical self-reference and an indication of its AMP counterpart:
The AMP page in turn should include a canonical link pointing back to the non-AMP page:
<link rel="canonical" href="https://example.com/page-a/" />