When a URL possesses a canonical tag pointing to a secondary URL that is also marked with a canonical tag aimed at a different resource, it creates a chain of canonicals (for instance, URL A points to URL B, which in turn points to URL C).
Why is this important?
The purpose of canonical tags is to clearly state the priority page for search engines. However, in these scenarios, the signal to search engines becomes mixed, often resulting in the canonical tags being disregarded as the engines strive to determine the correct priority URL independently.
An adverse outcome of such confusion could be search engines indexing undesired URLs, escalating the issues related to content redundancy.
What does the Optimization check?
Loud Interactive's Optimization will be activated for any internal URL containing a canonical link element that specifies another URL with its canonical tag.
Examples that trigger this Optimization:
Take the URL: https://example.com/page-a
This Optimization would trigger if the page contains a canonical link element pointing to another internal page:
<link rel="canonical" href="https://example.com/page-b" />
...and if this target URL https://example.com/page-b has its canonical link element pointing to a third internal page:
<link rel="canonical" href="https://example.com/page-c" />
These examples illustrate issues with canonicals set in the HTML, but they can also arise with canonicals determined through HTTP headers or a combination of both these methods.
How do you resolve this issue?
The canonical settings in this case are misconfigured and require attention to correct. Initially, determine if URL A should indeed point directly to URL C as the canonical, and then update the canonical tag as necessary. If URL B is the proper canonical for URL A, leave the canonical for URL A untouched, but ensure URL B's canonical tag points to itself.
Each instance of this problem will need individual analysis and resolution.