What it is
A relative canonical works until something resolves it wrongly, for example on a staging domain or behind a proxy. I use absolute URLs so there is no ambiguity about which page I mean. Canonical uses a relative path. Ambiguity can cause misresolution, especially with parameter/protocol variants.
Why does relative (not absolute) canonical matter for AI search?
Ambiguity can cause misresolution, especially with parameter/protocol variants.
How do you fix it?
Use absolute https URLs.
How do you find it on your site?
- View source and check whether the canonical href is absolute or relative.
- Crawl the site and flag relative canonicals.
- Confirm they resolve to the intended absolute URL.
- Switch them to fully qualified https URLs.
Which ranking and citation factors does it touch?
Absolute canonicals remove the risk of resolving to the wrong host, which would split or misassign signals.
What is the impact?
Low-medium. Inferred from best practice.
What is the evidence?
Use fully-qualified canonical URLs. Google Search Central, Consolidate duplicate URLs (canonicalization)
Sources
Frequently asked questions about relative (not absolute) canonical
What does "Relative (not absolute) canonical" mean?
Canonical uses a relative path.
How do you fix relative (not absolute) canonical?
Use absolute https URLs.