Quick answer
Use one canonical link element per HTML page so the preferred URL is unambiguous. NOTABIS reports multiple-canonical-tags when the measured document contains more than one link[rel="canonical"]. Remove accidental duplicates and verify that the remaining target matches your canonical strategy.
What the issue means
A canonical link points search engines toward the preferred representative of similar URLs:
<link rel="canonical" href="https://example.com/guides/tyre-storage">
Two tags can contain the same value or different values. Either can indicate that separate layouts, plugins, or application components are writing metadata independently. Multiple canonicals on different pages are a different issue from multiple elements on one page.
Why it matters for SEO
Search engines may choose one canonical signal or select a different URL based on other evidence. Conflicting declarations make consolidation less predictable and can leave users landing on an unintended representative. The count is not a standalone ranking penalty; correctness and consistency matter more than removing a warning mechanically.
How NOTABIS detects it
The multiple-canonical-tags rule counts link[rel="canonical"] elements in the measured HTML and records a page-level issue when the count is greater than one. It does not compare values, follow the targets, or decide which declaration is correct. Other checks cover missing, off-origin, redirect-conflicting, and noindex-conflicting canonicals.
How to check it yourself
Inspect View Source and the final DOM for every canonical element. Resolve relative URLs and request each target, checking status, redirects, content, and indexability. Search layout files, SEO plugins, and client-side route code for duplicate output.
How to fix it
Choose one canonical owner and emit one accurate tag from the page’s routing or content source. Remove duplicate tags from nested layouts and keep internal links and sitemaps aligned with the chosen URL.
<link rel="canonical" href="https://example.com/guides/tyre-storage">
Do not point every page to the home page or use a canonical as a replacement for a redirect. Recheck the public response after deployment and allow search engines time to process the updated signal.
When this is intentional or does not need fixing
A transient client-side route can briefly contain stale and new metadata during navigation, although the settled document should expose one clear canonical. A non-HTML response does not need canonical markup. Keep only one declaration even when two generators currently produce the same URL.
Related issues
Review canonical URLs present, missing canonical URLs, canonical and redirects, and duplicate content.
Run a NOTABIS audit
NOTABIS counts canonical link elements in each measured page and shows the response where duplicate declarations were found.