Canonicalization Error

A Canonicalization error occurs when the same webpage is able to be loaded from multiple URLs.


For human beings, the above URLs are all one and opens the same site when entered on the browser. However for the search engines all above are different URLs having similar content.

More detailed explanation:
Suppose your website is – Go to your browser and type it in, and your homepage will show up. Now if you have canonicalization error, if you go to the browser again and type in and your same page shows up. Google or any other search engiens will see the /index.html as the same page as home page and is going to render what your webpage will render from that address. Now in this case you can say you have two canonicalization error.

Worst scenario is when you have four such errors. The above URLs I wrote are with www, what if they are also directing in the absence of www.

As search engines see all these pages as different pages and they have same content, this is where you’re going to run into a major duplicate content penalty that could really squash your ranking. So duplicate content does not only arise when you copy content from some other website and paste into your site but also because of such error.

Google has to decide which url is the best represented from the possible options. Usually this would see the page with the most back links (internal and external) displayed in the search results, and so for most webmasters the problems remain hidden.

The most significant disadvantage of canonical url problems is that any link juice is split between several possible options and therfore not maximising the full ranking potential of the page.

How to eliminate the Canonicalization error?

Very simple.

To prevent the problem on an Apache server with rewrite enabled, place the following code in your .htaccess file:

To redirect from the non-www version to the www version

RewriteEngine on
RewriteCond %{HTTP_HOST} ^
RewriteRule (.*)$1 [R=301,L]

To redirect from the www version to the non-www version

RewriteEngine on
RewriteCond %{HTTP_HOST} .
RewriteCond %{HTTP_HOST} !^
RewriteRule (.*)$1 [R=301,L]

To redirect from to

RewriteEngine on
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9} /.*index.html HTTP/
RewriteRule ^(.*)index.html$ /$1 [R=301,L]

To do the same for index.php simply replace .html with .php in the code.

Please note above is only applicable for Apache Servers, the codes differ for Windows Server and ASP.

Hope this helps


This is just the experiment I did apart from the above post. I just checked for some keywords related to post and what I saw was amazing and pictures. See for yourself the ranking of this post without any backlinks. This is the power of unique content.

Ranking 1st for the keyword as mentioned below in the search box


Ranking 2nd for the Keyword how to avoid canonicalization error – Proof Below



Ranking 3rd for the keyword Rectify Your Canonicalization Error – Proof Below