What does the canonical URL mean in Google Search Console?

Q: What does the canonical URL mean in Google Search Console?

The canonical is the URL Google indexes from a set of duplicates. Here is where Search Console shows your choice and Google's, and how to fix a mismatch.

When several URLs show the same or nearly the same content, Google indexes one of them, the canonical, and treats the others as duplicates. In URL Inspection, Search Console shows two values: the user-declared canonical your page asks for, and the Google-selected canonical Google actually chose. Your declaration is a strong hint, not an instruction. When the two differ, something else on your site is pointing Google the other way.

Where Search Console shows canonicals

URL Inspection, under Page indexing: the user-declared canonical (from a rel="canonical" tag, an HTTP header, a sitemap or other methods) next to the Google-selected one. Google notes the selected value can be a few hours behind the index, and canonical details only appear when the canonical sits in a property you own.
The Page indexing report, through three reasons: Duplicate without user-selected canonical (you declared nothing, Google picked), Duplicate, Google chose different canonical than user (your choice was overruled) and Alternate page with proper canonical tag (working as intended).
The Performance report, indirectly: clicks and impressions on duplicates are credited to the canonical. A URL showing no traffic may simply be the duplicate of the one that collects it, so inspect before you conclude it gets nothing.

What Google weighs

Signal	How Google rates it
301 redirect to the preferred URL	Strong
`rel="canonical"` link element or HTTP header	Strong
Listing the URL in a sitemap	Weak
HTTPS rather than HTTP	Preferred, unless the HTTPS version has certificate or redirect problems
Membership of a reciprocal `hreflang` cluster	Preferred over a URL outside it

Combining signals makes your choice more likely to stick. Underneath all of them, Google decides which pages are duplicates by how similar their content is.

Why Google picks a different URL

Your signals disagree. The canonical tag says one URL, your navigation links to another and the sitemap lists a third.
The pages are not really duplicates. Google judges duplicates by their content, so a canonical pointing at a page that says something different is likely to be overruled.
HTTPS problems such as an invalid certificate, or an HTTPS page redirecting to HTTP, make Google prefer HTTP.
Conflicting declarations, such as a different URL in the HTML tag and the HTTP header, or a JavaScript-set canonical that differs from the HTML.

How to fix a mismatch

Pick one URL per piece of content, on HTTPS.
Give it a self-referencing canonical with an absolute URL, through one method only.
Link internally to that URL everywhere: menus, breadcrumbs, related links, pagination.
List only canonical URLs in your sitemap and in hreflang annotations.
301-redirect duplicates you do not need at all.
Do not canonicalise with robots.txt, noindex or the removals tool: they block or hide pages rather than choose between them.
Re-inspect after Google has recrawled the page.

When two different pages compete for the same searches, that is a different problem, and a canonical is the wrong tool. See the cannibalization playbook.

How AutoPSEO helps

Checking canonicals one URL at a time does not scale. AutoPSEO's bulk URL Inspection inspects a sitemap, a pasted list or a file of up to 500 URLs per run through Google's URL Inspection API and marks each one Match or Different, depending on whether Google's canonical agrees with yours, so a whole template can be checked at once and exported as CSV. The Cannibalization report finds queries where several of your pages split the clicks.

Sources: Google's canonicalization guide, URL Inspection tool help, Page indexing report help and Performance report dimensions help.