1.3 CanonicalisationMediumVerified
Protocol mismatch in canonical
An http canonical on an https page, or the reverse, points at the wrong version of the URL. After moving to https, every canonical should use https.
What it is
HTTP canonical on an HTTPS page or vice versa.
Why it matters
Splits consolidation across protocols.
How to fix it
Canonicalise to HTTPS consistently.
How to find it on your site
- Check the protocol of each canonical against the page it sits on.
- Flag any http canonical on an https page.
- Update canonicals to https.
- Confirm the https version is the one that returns 200.
Cross-reference to ranking and citation factors
A protocol mismatch can canonicalise to a URL that redirects, undermining the consolidation and adding a hop.
Impact
Medium. Direct.
Evidence
Keep canonical protocol consistent (HTTPS). Google Search Central, Consolidate duplicate URLs (canonicalization); Google Search Central, Secure your site with HTTPS
Sources