Quick answer
Sitemap should list canonical URLs.
Sitemap Non-Canonical URLs
Sitemap should list canonical URLs. Listing non-canonical or duplicate content URLs dilutes signals.
Common causes
- HTTP in sitemap, site is HTTPS.
- www vs non-www mix.
How to fix
- Use canonical URL (HTTPS, one host).
- Match canonical tag.
FAQ
- Canonical in sitemap?
- Yes; list canonical only.
- HTTP or HTTPS?
- Match site.
Fix it now
Try in validator (prefill this example)