Indexability and crawling
How to fix canonical tag problems
A canonical tag names the real URL for a page when the same content is reachable more than one way. Getting it wrong is quieter than most SEO faults: nothing on the page looks broken, and its value quietly goes to the wrong address — or to one that cannot rank at all.
Pages with no canonical
The same page is often reachable more than one way: with a tracking parameter, with and without a trailing slash, through a category path. A canonical tag tells Google which URL is the real one, so all that value lands on a single address instead of being split.
What it is, and what it costs
<link rel="canonical" href="..."> in the page head names the preferred URL for a page. Without it, Google may treat each variant as a separate page, divide the ranking signals between them, and sometimes index the version you did not want. The fix is cheap and the pages look fine either way, which is why it gets missed.How to fix it
- WordPress: Yoast and Rank Math add a self-referencing canonical automatically. If they are off, turn canonical output on, and set a manual canonical on any page that should point elsewhere.
- Shopify: themes output canonicals by default; check that collection and filtered URLs point at the clean product or collection URL.
- Hand-coded: add
<link rel="canonical" href="https://yoursite.com/this-page">to each page head, pointing at that page's own clean URL.
How to check your site
View source and look for rel="canonical". Crawl the site to find pages that have none, or whose canonical points somewhere odd.
Related: canonical pointing at a dead URL, and pages with two canonicals.
Questions people ask
- Should a page canonical to itself?
- Usually yes: a self-referencing canonical is the normal, safe default for a page that should rank on its own.
Canonicals pointing at a dead URL
A canonical is meant to name the real version of a page. When it points at a URL that is redirected, missing, or itself blocked from search, it hands your page's value to something that cannot rank, which is worse than no canonical at all.
What it is, and what it costs
rel="canonical" aimed at a dead or non-indexable target. Google follows the instruction, tries to consolidate the page into a URL that returns 404 or 301 or carries noindex, and the original can drop out of results as a result. It usually comes from a site migration where canonicals kept pointing at old URLs.How to fix it
Point each canonical at a live URL that returns 200 and is itself indexable, almost always the page's own clean address.
- WordPress / Shopify: if canonicals are set manually or by an SEO plugin, correct the target; after a migration, regenerate them against the new URLs.
- Hand-coded: update the
hrefto the current, working URL.
How to check your site
Crawl the site and check where each canonical resolves; flag any that hit a 3xx, 4xx, or a noindexed page.
Related: adding a canonical, and two-canonical conflicts.
Questions people ask
- Can a canonical point to another page on purpose?
- Yes, when two pages are duplicates and you want one to win. The target just has to be live and indexable.
Two canonicals on one page
When a page declares more than one canonical URL, search engines cannot tell which you meant, so they ignore both and pick for themselves. It is usually a theme and a plugin each adding their own.
What it is, and what it costs
rel="canonical" links on one page is a contradiction. Google discards the signal and guesses which URL to index, which may not be the one you would have chosen. The page looks normal; the conflict is only in the source.How to fix it
Leave exactly one canonical per page.
- WordPress: the common cause is an SEO plugin and the theme both outputting one. Turn off the theme's canonical (or the duplicate plugin) so only one remains.
- Hand-coded: remove the extra
<link rel="canonical">so a single tag is left.
How to check your site
View source and count rel="canonical": more than one is the problem.
Related: adding a canonical, and broken canonicals.
Questions people ask
- Which one does Google keep if there are two?
- It may keep either or neither. Do not rely on order; leave one.
Does your site have this?
Check your site to see which pages are missing a canonical.
See also
- How to fix XML sitemap problemsA sitemap is how search engines discover pages your own links do not lead to well, and how they learn something changed. Two things go wrong with it: there is not one, or the one you have lists URLs that do not work.
- How to fix a page accidentally set to “noindex”If a page you care about is nowhere in Google, not even when you search its exact title, a noindex tag is the first thing to rule out. It is one line, it overrides everything else you do for that page, and it usually got there by accident.
- How to fix a robots.txt that blocks your whole siteDisallow: / in your robots.txt is the fastest way to disappear from search. It asks every crawler to skip the whole site at once, and it is a common leftover from launch day.
- How to fix redirect chains on your siteA redirect that points at another redirect makes the reader wait through every hop, and a bit of the value from the original link leaks away at each one. Chains build up quietly over years of moving pages around.