Canonical Tag Issues
What This Means
Canonical tags tell search engines which version of a page is the "primary" version when multiple URLs contain similar or identical content. Incorrect canonical tags can cause indexing problems and dilute ranking signals.
Impact:
- Wrong pages indexed
- Duplicate content penalties
- Diluted page authority
- Incorrect pages ranking (or not ranking)
How to Diagnose
1. Check Page Source
<link rel="canonical" href="https://example.com/correct-page/" />
Questions to ask:
- Is canonical tag present?
- Does it point to the current URL or different URL?
- Is the canonical URL accessible (not 404)?
- Is it the correct primary version?
2. Google Search Console
- Use URL Inspection tool
- Check "Canonical tag" under Coverage
- Compare "User-declared canonical" vs "Google-selected canonical"
- Mismatches indicate problems
3. Crawl Analysis
Use Screaming Frog or similar:
- Export all canonical tags
- Check for self-referencing vs cross-page canonicals
- Identify canonicals pointing to 404s
- Find pages without canonicals
Common Issues
1. Missing Canonical Tags
Problem: No canonical specified, search engine chooses.
Fix:
<head>
<link rel="canonical" href="https://example.com/page/" />
</head>
2. Wrong Canonical URL
Problem: Canonical points to wrong page.
Examples:
- All pages canonical to homepage
- Canonical to different product
- Canonical to old URL
Fix: Update canonical to point to the current page's canonical URL.
3. Canonical to Non-Indexable Page
Problem: Canonical points to:
- 404 page
- Redirected URL
- noindex page
Fix: Point canonical to live, indexable page.
4. HTTP vs HTTPS Mismatch
Problem:
<!-- Page is HTTPS, canonical is HTTP -->
<link rel="canonical" href="http://example.com/page/" />
Fix: Ensure canonical matches site's protocol (HTTPS preferred).
5. Trailing Slash Inconsistency
Problem: Site uses /page/ but canonical uses /page
Fix: Be consistent with trailing slashes across site.
6. Pagination Canonicals
Problem: All paginated pages canonical to page 1.
Better approach:
- Each paginated page is self-canonical
- Use rel="prev" and rel="next" (optional now)
- Or use single long page
General Fixes
Self-Referencing Canonicals
Best practice is every indexable page has a self-referencing canonical:
<!-- On https://example.com/products/widget/ -->
<link rel="canonical" href="https://example.com/products/widget/" />
Consolidating Duplicate Content
When content exists at multiple URLs:
- Choose the primary URL
- All duplicates canonical to primary
- Optionally 301 redirect duplicates
Query Parameter Handling
For pages with URL parameters:
/products?sort=price
/products?sort=name
/products?page=2
Options:
- Canonical to base URL:
/products - Google Search Console parameter handling
- Server-side canonical logic
Platform-Specific Guides
| Platform | Guide |
|---|---|
| Shopify | Shopify Canonicals |
| WordPress | WordPress Yoast SEO |
| Squarespace | Squarespace SEO Settings |
| Wix | Wix URL Settings |
Verification
After fixes:
- Inspect pages in Search Console
- Check Google-selected canonical matches your intention
- Wait for re-crawl and re-indexing
- Monitor indexed pages count
Tools
- Google Search Console
- Screaming Frog - Bulk canonical analysis
- Ahrefs Site Audit - Canonical issues report