This error appears when a page has no canonical URL defined. Here's what it means and how to fix it.
Without a canonical, Google may split a page's authority across multiple URLs showing the same content. That weakens the rankings of all of them instead of concentrating the strength in a single one.
Users won't notice this error directly, but they may come across duplicate versions of the same page in search results. That creates confusion and undermines your site's credibility.
Without a clear signal, Google may index versions of the page that aren't the ones you want to show. Basically, you lose control over what appears in search results.
If this error showed up in your audit, here are the steps to leave it behind.
Before adding anything, you need to be clear about which URL the canonical should point to. It's usually the clean address, without parameters or variations. Review your site's URLs and identify which version you want Google to index.
Once the primary URL is clear, add the tag inside the page's <head> using the format <link rel="canonical" href="https://yourdomain.com/primary-url/">. You can do this through the SEO plugin you use (Yoast, Rank Math, etc.) or directly in the code.
Once the change is published, open the page source and look for <link rel="canonical"> inside the <head>. Verify that it appears and that it points to the correct URL.
To help you better understand this type of error and why it happens, we include additional materials that expand the explanations, guide with examples, or show alternative methods.
Having a canonical tag pointing to another URL can cause Google to ignore your page and rank a different address instead.
View resourceHaving more than one canonical tag on the same page creates a conflict. Google may ignore them all and decide on its own.
View resourceA page with noindex is invisible to Google. It won't appear in search results no matter how well optimized it is.
View resourceAudit your website for free and discover if this and other SEO errors are affecting your ranking.