5 common errors with the rel = canonical

rel canonicalrel = canonical is useful for webmasters to tell Google what is the correct version of a page whose content is duplicated across multiple different URLs.

The tool allows the consolidation of ownership of the various duplicates to the canonical version, such as inbound links, and allows you to decide which URL will be displayed within the search results.

However, this is an instrument whose incorrect implementation can also lead to serious problems in the indexing of the site. Let's look at what may be the most common mistakes that can happen.

Error 1: rel = canonical to the first page of a series of pages

Imagine you have an article on multiple pages:


Specify within the instruction rel = canonical of the page 2 (and later) the URL of the first page is not a correct way to use the rel = canonical.
The consequences are potentially very serious: the following pages might well not be indexed.
In the case of an article on multiple pages, the Google recommendations are those to insert an instruction of canonical page on a non-paged article. For example:
<link rel=canonical href=“http://www.example.com/article/all” />

Alternatively, it is recommended to use the instructions rel = next and rel = prev. For example, on page 2, instead of the rel = canonical enter the following instructions:


<link rel=prev href=“http://www.example.com/article/pag-1” />
<link rel=next href=“http://www.example.com/article/pag-3” />

Error 2: relative URLs instead of absolute ones

The tag <link> also accepts relative and absolute URL. The first specifies the path to the page linked from the current page. For example, "images/logo.jpg" indicates that we need to go from the current folder in the folder "images" and then find the file "logo.jpg". Absolute URLs do contain the full path from the root directory of the site, ex."http://www.etc".

In the case of rel = canonical, specify a relative address as canonical, risks leading the search engine to ignore the instruction given, thus defeating our action.

For example, if on the page "http://www.example.com/article" the instruction is written in this way:


<link rel=canonical href=“www.example.com/article” />

The canonical URL is interpreted as "http://www.example.com/article/www.example.com/article." Here we have the correct way to write the statement:


<link rel=canonical href=“/article” />



<link rel=canonical href=“http://www.example.com/article” />

Error 3: instruction rel = canonical unintentional or double

In the case of web pages whose source code has been copied from another source (or if you used a template for the creation of HTML), it can happen that it is stored for error even an irrelevant instruction rel = canonical, probably to the page from which you copied the source code.

It can also happen to put a double instruction rel = canonical is the case for instance of the CMS functionality with plugins for SEO, which often also run the rel = canonical unbeknownst to the webmaster who installed them. In case of multiple indications, Google will most likely ignore both the instructions given.

In both cases, the problem can be identified by carefully examining the HTML source code. It 'important to make sure you look deeply within the <head> tag, because the instructions may be scattered or not obvious.

Error 4: category page with rel = canonical to an article

In the hypothetical case where a category page shows extensively the content of an article (for example, a featured article), you might think about putting the instruction of canonical page by page category to article page.

As a result of this, the category page will not show up in search results. If you want the category page is displayed within the search results, Google recommends to insert a canonical page instruction to the page itself, or alternatively not to include any instructions rel = canonical.

Error 5: rel = canonical in the <body> tag

rel = canonical Instruction should be inserted only in <head> tag. In addition, to minimize the recognition errors of HTML, it should be incorporated as early as possible. If by chance the rel = canonical is present inside of the <body> tag, simply will be ignored by Google.



To compile the instructions rel=canonical correctly is important:
verify that the text is actually identical to the canonical version to which we want to point;
check that the rel = canonical is specified does not more than once within the <head> tag;
check that the URL provided as canonical is existing;
avoid inserting rel = canonical by category page to Articles.

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