“Duplicate without user-selected canonical” means Google found several URLs serving substantially the same content, you did not declare which one is authoritative, so Google picked one itself.
The excluded pages are not penalised. They are consolidated into whichever URL Google selected. The risk is that its choice may not be yours.
Why it happens
- No canonical tag at all, so nothing indicates a preference.
- Self-referencing canonicals on every duplicate, which tells Google each is authoritative and resolves nothing.
- Parameters producing URL variants of the same page.
- Both www and non-www, or http and https, resolving without redirects.
- Trailing slash inconsistency, where both forms serve content.
- Uppercase and lowercase variants of the same path.
- Products reachable through multiple category paths with no canonical resolving them.
The last is the standard ecommerce case, and on Shopify specifically it has a well-known shape covered under Shopify duplicate content.
Why leaving it to Google is risky
- The selected URL may be a parameter version rather than your clean URL.
- It may be one you did not intend to expose publicly.
- The selection can change over time, producing ranking instability.
- Internal links and sitemaps pointing elsewhere weaken the consolidation.
- You lose the ability to reason about which page is competing.
Diagnosing it
- Export the affected URLs and use URL Inspection to see which URL Google selected.
- Compare the selected URL with the one you would have chosen.
- Look for the pattern: parameters, protocol, slash or case will explain most of them.
- Check whether internal links point at the intended canonical or at a variant.
- Confirm your sitemap lists only the URLs you want indexed.
Fixing it
- Declare a canonical on every page, pointing at the intended URL rather than at itself where duplicates exist.
- Redirect rather than canonicalise where variants serve no purpose, such as protocol or www duplicates.
- Standardise trailing slashes and casing at server level.
- Make internal links use the canonical form, since contradictory links undermine the declaration.
- Handle parameters deliberately, rather than allowing every combination to serve content. See parameter URLs.
- Differentiate where the pages should genuinely both exist, since near-identical pages will keep being consolidated otherwise.
Every signal must agree: canonical tag, internal links, sitemap and redirects. One contradiction is usually enough for Google to substitute its own judgement.
Frequently asked questions
Is this a duplicate content penalty?
No. There is no penalty for duplicate content of this kind. Google consolidates the duplicates into one URL. The cost is loss of control over which one, not a sanction.
How is this different from “Alternate page with proper canonical tag”?
In that status you declared a canonical and Google honoured it, which is correct behaviour. Here you declared nothing usable, so Google chose. The difference is who made the decision.
Google chose the wrong URL. How do I change it?
Declare the canonical explicitly, then align every other signal with it: internal links, sitemap entries and any redirects. A canonical contradicted by your own links is frequently ignored.
Should I redirect or canonicalise?
Redirect where the duplicate has no reason to exist for users, such as protocol or www variants. Canonicalise where users need the variant, such as a filtered view they arrived at deliberately.
Consulting CTA
If Google is selecting canonicals you did not intend, book an SEO consultation for a duplicate and canonical review of your URL structure.