Alternate page with proper canonical tag: meaning and fix

What the status means

Google's definition: this page correctly points to the canonical page, which is indexed, so there is nothing you need to do. In other words, three things are true at once:

1. Google crawled the URL and found it's a duplicate or a variant of another page.
2. The URL has a rel="canonical" tag naming that other page.
3. Google agreed, and indexed the other page instead.

That's canonicalization working exactly as intended. The duplicate isn't penalised; its signals are consolidated onto the canonical, and searchers are shown the canonical URL. Google's documentation is clear that some duplicate content on a site is normal and isn't a violation of its spam policies.

https://example.com/shirt?color=blue
  <link rel="canonical" href="https://example.com/shirt">
→ listed as "Alternate page with proper canonical tag"
→ https://example.com/shirt is the URL that gets indexed

Common URLs that belong here

On most sites, this list is full of URLs like these, and every one of them is fine:

• Tracking and campaign parameters: ?utm_source=newsletter, ?gclid=…, ?fbclid=….
• Sorting and filtering: ?sort=price, ?page_size=48, or filtered category views.
• Product variants that canonicalise to the main product page.
• The same product under different paths, such as a product reached through a collection or category URL.
• AMP pages that point to their non-AMP version, and print or "amp" variants.
• Separate mobile URLs, such as m.example.com, that point to the desktop page.

A large number here isn't a problem either. Shops and sites with faceted navigation commonly have far more alternate URLs than real pages.

When it is a real problem

The status only means the canonical tag was followed. It doesn't judge whether the canonical was the right choice. Look closer if you find any of these in the list:

• A page you want in search. If a unique article, product or landing page is here, its canonical points at something else, and that is why it isn't indexed.
• Every page pointing to the homepage. A theme or plugin that hard-codes the homepage as the canonical on every template removes the whole site from search except one URL.
• Pagination pointing to page 1. Page 2, 3 and onward of a category list different products or posts, so they shouldn't canonicalise to the first page. Each paginated page should have a self-referencing canonical, or the items only linked from later pages become harder to reach.
• Language versions pointing to each other. A German page whose canonical is the English page tells Google the German page is a duplicate. Each language version should be canonical to itself and linked with hreflang tags.
• Canonicals to the wrong protocol or host, such as http:// or a staging domain, left over from development or a migration.

How to check a URL

Export the example URLs from the report (Indexing, then Pages, then Alternate page with proper canonical tag) and sort them by pattern. Parameter URLs can be skipped. Look at anything without a parameter, because those are the URLs most likely to be real pages.

For a single URL, the URL Inspection tool in Search Console shows both the User-declared canonical (your tag) and the Google-selected canonical. For a quick look at the tag, the title and everything else on the page, use the free SEO Checker.

To see the whole picture, crawl the site and group its pages by content. A duplicate content check shows which URLs share text, which canonical each one declares, and which URL in each group should be kept:

Two questions settle each URL:

1. Is this page really a duplicate of the page its canonical names? If yes, it's working.
2. Is the canonical the URL you want in search? It should return 200, be indexable, and not redirect. A canonical pointing to a redirect or a noindex page sends conflicting signals.

How to fix a wrong canonical

1. Find where the tag comes from. View the page source and search for canonical. It's usually written by your SEO plugin, theme or platform, not typed by hand. Also check the HTTP Link header with the HTTP Header Checker, since a canonical can be sent there too.
2. Make unique pages self-referencing. A page that should be indexed should name its own URL as canonical: same protocol, hostname, path and trailing slash as the URL in your sitemap.
3. Remove duplicates of the tag. A theme and a plugin both adding a canonical, with different URLs, is a common cause. Keep one.
4. Use absolute URLs. Google supports relative canonicals but recommends absolute ones, because relative URLs can cause problems, for example when a test copy of the site gets crawled.
5. Check JavaScript doesn't change it. Google recommends putting the canonical in the HTML source and making sure scripts don't rewrite it.
6. Request indexing for the corrected pages with URL Inspection. Google may keep pages in a duplicate cluster for a while after a change; its documentation mentions up to two weeks.

For more on how canonical tags work and how they compare with redirects and noindex, see Canonical tags: what they are and how to use them.

Shopify and WordPress

Shopify

Shopify themes output a canonical on every page. Products are reachable through collection paths such as /collections/shirts/products/blue-shirt, and those URLs canonicalise to /products/blue-shirt, so they appear in this report. That is the intended setup. Variant URLs (?variant=…) and filtered or sorted collection URLs show here for the same reason. Look closer only if a theme edit has changed the canonical_url output in theme.liquid.

WordPress

WordPress and SEO plugins such as Yoast and Rank Math add self-referencing canonicals by default, so parameter URLs, comment-reply links and attachment variants commonly show here. If a real post appears, open it in the editor and check the plugin's advanced settings for a custom canonical URL; that field overrides the default and is easy to set by mistake.

Questions