1. Incorrect or conflicting canonical tags:
Pointing to non-existent or 404 pages
Multiple canonical tags with different URLs on one page
Pointing to a different domain entirely
Fix: Double-check canonical tags, use only one per page, and use absolute URLs.
2. Canonical chains or loops
When Page A points to Page B as canonical, but Page B points back to A or another page, creating a loop.
Fix: Ensure canonical URLs always point to the final, preferred version of the page.
3. Using noindex and canonical tags together
Sending mixed signals to search engines. Noindex means don’t index the page at all, making canonicals irrelevant.
Fix: Use canonical tags for consolidation and noindex for exclusion.
4. Canonicalizing to redirect or noindex pages
Pointing canonicals to redirected or noindex pages confuses search engines.
Fix: Canonical URLs should be 200 status and indexable.
5. Ignoring case sensitivity
Inconsistent URL casing can cause duplicate content issues.
Fix: Keep URL and canonical tag casing consistent.
6. Overlooking pagination and parameters
Paginated content and parameter-heavy URLs can cause duplication if mishandled.
Fix: Use canonical tags pointing to the first page or “View All” for pagination, and keep parameters consistent.
Key Takeaways
It’s unlikely the complete list of 40+ signals used to determine canonical URLs will be made publicly available.
However, this was still an insightful discussion worth highlighting.
Here are the key takeaways:
Google uses approximately 40 different signals to determine canonical URLs, with rel=”canonical” tags and 301 redirects being among the strongest indicators
When signals conflict, Google falls back on secondary signals to make its determination
Clear, consistent implementation of canonicalization signals (tags, redirects, sitemaps, internal linking) is crucial
Common mistakes like canonical chains, mixed signals, or incorrect implementations can confuse search engines
Hear the full discussion in the video below:
Featured Image: chatiyanon/Shutterstock