Canonical Issues In SEO: How To Find & Fix Them

Canonical issues in SEO occur when two or more URLs display the same or very similar content without being properly canonicalized.

This confuses search engines!

The reason?

They cannot easily tell which of those similar URLs to prioritize. They may also see your pages as duplicate content.

The result?

Lower SEO performance.

To avoid all this, you need to know how to set up canonical tags properly and how to prevent your website from facing canonical issues.

What Are Canonical Issues In SEO?

In SEO, canonical issues in a website arise when two or more URLs that display very similar or identical content are not canonicalized properly. This means that canonical tags are wrong or non-existent. As a result, search engines cannot tell which is the core version of a page and often index the wrong URL.

A Bit Of ‘Canonical’ Background

The canonical tag was introduced in 2009 to help manage duplicate content. It marks which is the ‘proper’ URL that search engines should index.

Canonical issues don’t just appear out of the blue. There are certain rather usual cases where duplicate content arises due to canonical errors.

As a result, SEOs follow standard procedures to protect a website and avoid wasting their crawl budget.

Examples Of Canonical Issues

To fine-tune your website for SEO, you are much better off taking care of canonicalization issues proactively. Here’s what you’ll usually come across:

1. Protocol & Host Name

A common canonical issue all SEOs know about lays in variations of the protocol and/or hostname (i.e., domain name):

• http vs. https → http://www.example.com vs. https://www.example.com
• www vs. non-www → www.example.com vs. example.com
• trailing slash vs. non-trailing slash → example.com/page vs. example.com/page/

All these URL variations must point to the same page to avoid canonicalization errors.

2. Parameters & Session IDs

This is a common issue in e-commerce sites or some content management systems. It happens when the same page appears under different URLs.

For instance:

• Sites using session IDs: example.com/widgets/index.php?sessionid=1234567
• Sorting/filtering parameters: example.com/products/silk-dress?variant=1234560 or example.com.gr/search?q=dress&type=product
• Tracking IDs: example.com/?source=travel_blog

Again, all these URL variations should be linked to their actual page.

3. Using Capitalization & LowerCase

URLs are case-sensitive. Everything after the host name should follow a consistent letter casing format across all URLs. Otherwise, it’s considered as a different URL.

Here’s what to avoid: example.com/greatbritain vs. example.com/GreatBritain

Such discrepancies are considered as separate URLs.

4. Different Page Locations On The Website

Pages can often appear in different locations within the same website. This is common in e-commerce stores where the same product page appears in various product categories.

In some e-commerce CMSs, depending on the category path a user has taken to view the product page, a single product may be available at a number of different URLs.

E.g.: example.com/shop/summer-clothes/silk-dress vs. example.com/shop/dresses/silk-dress

These are breadcrumb trail URLs. Though it’s not a recommended approach if your e-shop is built in this way, you must let Google know that all such URLs refer to the same product page. Otherwise, they could be considered as problematic duplicates.

Why Are Canonical Issues Problematic?

For SEO, canonical issues are problematic for a few key reasons:

1. Indexing Your Non-Preferred URL

Google doesn’t commonly index duplicate content. So, if you give it different URLs that lead to the same page without any instructions, you’ll have a ‘random’ google-selected canonical indexed.

Let’s look at the Silk Dress example above:

Your product: Silk Dress that’s shown on a product page with URL: example.com/products/silk-dress - is now available in gray, blue, and white.

Users who choose a color variation, get to a new URL.

So, let’s say that the URL for your silk dress in gray is: example.com/products/silk-dress?variant=1234560

...and the silk dress in white, the URL is: example.com/products/silk-dress?variant=9875643

You wouldn’t want Google to index any variant URLs. After all, maybe you won’t have any gray or white silk dresses left a few months down the road. Instead, you may have new brown and black shades (with new URL parameters).

So, clearly show Google which your standard product page is - for all current or future variations and sizes. You’ll basically need to index the core product URL: example.com/products/silk-dress - the canonical version of your page.

2. Dispersing Your Link Juice

If your content is accessible through multiple URLs, 3rd party websites may link to different versions, spreading your link equity across several pages and weakening its overall impact.

3. Disempowering Your Backlink Profile

Suppose Google selects the wrong URL as the canonical version.

In that case, it could only consider backlinks or internal links to your canonicalized URLs and ignore everything else. This can significantly disempower your preferred canonical page and hurt your rankings.

How To Determine If Your Site Has Canonical Issues

To maintain a strong SEO performance, you should run regular canonical checks. Common methods to identify canonicalization issues include:

1. Check canonical tags with Google Search Console
2. Perform thorough website audits
3. Manually check for protocol/hostname discrepancies
4. Use crawling tools
5. Inspect your indexed pages

Let’s now elaborate.

1. Check Your Canonical Tags With Google Search Console

One of the simplest ways to detect canonical issues is through Google Search Console (GSC).

Here, you can check canonical tags for a single URL or your entire website.

Check Canonical Tags Of A Single URL

• In GSC, open the URL Inspection Tool.
• Enter the URL you want to inspect and run the test.
• Scroll down to the Page Indexing section and check the Google-selected canonical field.

If the ‘Google-selected canonical’ tag and the ‘user-declared canonical’ tag do not match, then this means that Google is indexing a different version of what you intended.

Check Canonical Tags Site-Wide

In GSC, from the left sidebar, expand the Indexing section and choose 'Pages.' At the Page Indexing report that comes up, scroll down to: Why pages aren’t indexed.

If your website has canonical-related errors, you’ll see them listed in either (or both) of the following categories:

a. Duplicate without user-selected canonical

This shows non-canonical URLs for pages with identical content but no canonical tag.

Solution: Add canonical tags to your preferred URL/page and its variations.

b. Duplicate, Google chose a different canonical

Google is ignoring your canonical directive and has chosen another page.

Solution: If you wish to have both pages indexed separately, you need to differentiate them by altering their page title, headings, content, and/or URL (and then redirect URL changes).

When finished, click ‘Validate Fix’ in GSC for every page and monitor until you ensure the issue is settled.

2. Perform A Website Audit

Website audits for SEO include canonical errors, along with any other issues that could impact your site's technical health.

Tools like Ahrefs or SEMrush help you run audits and canonical checks to discover problems, like:

a. Non-canonical URLs In XML Sitemaps

This means that your sitemap includes pages that are not marked as canonical, which can confuse search engines.

b. Canonical URLs With Http > Https Mismatches

Canonical URLs pointing to Http instead of Https - create security concerns and indexing problems.

c. Canonical URLs With 3XX, 4XX, Or 5XX Status Codes

These errors indicate your canonical URLs are either being redirected or are broken, both of which can hurt SEO.

Regular site audits are essential for smooth site performance.

3. Manually Check For Http/Https & www/non-www Variations

To check this manually, simply type all possible versions of your homepage URL into a browser:

http://www.example.com
https://www.example.com
http://example.com
https://example.com

All these URLs should redirect you to your preferred version of your home page. If not, you’ll need to fix canonical errors by setting proper redirects and using consistent canonical tags.

4. Use A Crawling Tool

SEO apps like Screaming Frog crawl your entire website, even if it has thousands of pages, and generate a comprehensive list of all URLs so that you can identify:

a. Duplicate content issues
b. Canonical chains (i.e., non-canonical URLs that redirect to each other)
c. Non-canonical URLs without the right tags

So, once you see all issues, you can start fixing them.

5. Search Google For Your Indexed Pages

For DIY SEO enthusiasts, another method to spot canonicalization issues is by typing:

site:yourwebsite.com

...into the search bar. This will give you a (nearly) full list of your indexed URLs in Google.

Are you seeing duplicates or other pages that shouldn't be indexed in SERPs? Then, you may be facing canonical issues.

This manual approach can sometimes reveal unexpected indexing or canonicalization issues that may be overlooked by audit and crawling tools. So, even professional SEOs use this method in some cases.

What Are Some Common Mistakes When Adding Canonical Tags?

To ensure high SEO performance, watch out for these common canonical tag errors:

1. Pointing To Non-Crawlable Or Non-Indexable URLs

All canonical URLs must be crawlable. So, check your robots.txt or your pages’ headers for any “noindex” tags.

2. Creating Canonical Chains

Double-check that the canonicalized page (i.e., the ‘variation’ of your preferred canonical page) has a canonical tag pointing to your preferred page and not to any other page or even itself.

Otherwise, you’ll create the so-called ‘canonical chains’ where Google often considers the last page on the chain as the canonical page worth indexing.

Follow this short checklist:

a. Point secondary page versions to your main, canonical page
b. Link your main canonical page to itself
c. If you detect a canonical chain, try to understand how it occurred in the first place (to avoid similar drawbacks in the future.)

3. Using Wrong URLs With Wrong Status Codes Or Http Protocols

All your canonical pages must return a 200 status code. Do not canonicalize to pages with 404s (page not found errors) or 301 - redirected URLs.

The same applies to the page protocol. Always use the https page versions in your canonical tags. You surely don’t want search engines to index a non-secure http and give your site an ‘insecure’ look.

4. Including Non-Canonical Pages In Your Sitemap

Only canonical pages should be included in your sitemap. So, check your sitemap and delete any non-canonical URLs.

5. Pointing Internal Links To Non-Canonical URLs

All your website links must point to the canonical URLs. Otherwise, you may confuse search engines. They won’t be certain which page version is your ‘good’ one. And thus, you’ll undermine your internal linking structure and anchor strength.

6. Using Hreflang Instead Of Canonical Tags

If you optimize a multi-language website, you’ll need to use both canonical tags and hreflang tags. They are 2 different things.

Hreflang tags indicate the regional and language variations of a page.

So, if you have a UK-based website in 2 different languages (let’s say German and Italian), your ‘About Us’ page would need some extra hreflang tags that would look like this:

<link rel=”alternate” hreflang=”fr” href=”https://www.example.com/fr/aboutus”>
<link rel=”alternate” hreflang=”de” href=”https://www.example.com/de/aboutus”>

If you’d like to localize your website for different regions speaking the same language, you’d need to add additional hreflang tags to indicate that.

For instance, the hreflang for your version aimed at British English speakers and UK users would be:

<link rel=”alternate” hreflang=”en_gb” href=”https://www.example.com/uk/aboutus”>

And for American English speakers and US users:

<link rel=”alternate” hreflang=”en_us” href=”https://www.example.com/us/aboutus”>

Google also recommends adding an extra “wild card” hreflang - the ‘x-default’ tag that indicates the fallback page shown to users when no other language version is an ideal match.

This is what it looks like:

<link rel=”alternate” hreflang=”x-default” href=”https://www.example.com/aboutus”>

Sounds complicated?

Fear not. The more you work on your canonical tags, the easier it becomes to streamline procedures, set recurring checks, and avoid confusions.

How To Fix Canonical Issues And Safeguard Your SEO Efforts

Here's how to fix common canonical issues:

1. Apply 301 Redirects

This is a solid and easy fix for http/https & www/non-www discrepancies. Simply make appropriate root redirects on a site-wide level and check that everything works fine.

2. Fix Canonicalization For Mobile & AMP Versions

URLs often change based on user device. So, if your website has a different mobile version, ensure that all your mobile pages are canonicalized.

Your mobile site URLs may look like this: m.example.com vs. example.com

Or, you may have an AMP website version. AMP stands for Accelerated Mobile Pages. It is an Open Source Framework that creates simple mobile websites that load almost instantly.

AMP sites come with URLs like: amp.example.com vs. example.com

Such mobile URL variations can easily create canonical issues. So, add canonical tags on all mobile pages pointing to their desktop counterparts.

3. Check That Your Syndicated Content Has Canonical Tags

When syndicating content across multiple sites, ensure your syndication partners include a “rel=canonical” tag pointing to the original content on your website.

This is a standard practice. In essence, it attests that no syndication partner has duplicate content. Plus, it prevents Google from ranking the syndicated version higher than yours.

How To Avoid Canonical Errors In SEO: Best Practices To Follow

Here’s what you need to do to keep your canonicals rolling smoothly:

1. Add Canonical Tags On Every Page

Standardize the procedure of adding self-referencing canonicals to each and every one of your pages. This is the best way to avoid canonicalization issues now and in the future.

2. Use Absolute URLs & Be Consistent

Your canonical tags should only have absolute URLs (e.g., https://www.example/page instead of just: /page). And always use either www or non-www versions throughout - do not mix the two. The same applies for your chosen trailing slash variation (i.e., either with / or without / - sitewide).

3. Check Your Canonical Tags Regularly

Schedule periodic canonical checks in your SEO checklist. Plus, when you implement extensive changes in your website structure or content, run a thorough check to ensure all your canonicals are working properly.

Wrapping up, note that streamling canonicals is just a piece of the SEO pie. There are many more website enhancements to account for extra visibility and higher conversions.

Are you looking for comprehensive SEO services? Book an SEO strategy call with Atropos Digital.