Canonical Url Errors with All-in-One SEO WordPress Plugin

All in One SEO Pack is a very popular wordpress plugin and does some SEO tweaks for optimizing your WordPress blog for higher search engine rankings. But as our pagerank dropped recently, investigation revealed that though there may be many causes for PR drop, some canonical url options might be reducing our google pagerank.

All in One SEO WordPress Plugin & Canonical Urls

Google recently introduced a Canonical url option which allows webmasters and bloggers to specify a canonical url in the HEAD of their html to publicly specify the preferred version of a URL. If your site has identical or vastly similar content that’s accessible through multiple URLs, this format provides you with more control over the URL returned in search results. Which basically means that if your single page is accessed by multiple urls, the canonical url option can help search engines identify and index the url of choice and avoid duplicate content Google penalization issues.

The FAQ reveals its a very powerful atribute to add to web pages and is hint that Google will honor strongly, and is willing to accept URLs which redirects as a canonical URL to index it.

We have been using the excellent All in One SEO Plugin for quite some while for blog SEO purposes. WP 2.7 has made it super easy to upgrade the plugins in one click and usually we upgrade to new plugin versions without actually looking into the options everytime we upgrade. Big mistake!

Upgraded plugins may check new options by default in the new upgrade, which you might never know without reading the changelog (which how many of us do?).

canonical urls

The recent upgrade of All in One SEO Plugin checked the canonical urls option by default. While this was a good step for a SEO plugin, it possibly reduced our Pagerank. Here is how….

Canonical Urls and Google Pagerank

We host our WordPress blog in a subdirectory called “Archives”. Its easy to host WordPress in an alternative directory. So the canonical url of the front page should be

<link rel="canonical" href="" />

while the hosted blog archives page should be

<link rel="canonical" href="" />

But when I looked into the source code of the main page and the archives page, both show this

wrong canonical url

which basically means that when search engines visit, the canonical url tells them / redirects them with information that the actual page of choice which we want to index is and that creates a whole lot of confusion in the search engines.

Its possibly occurred on our blog because WordPress address and Blog address are the same in the WP admin settings, so maybe the plugin does not recognize the occurence of the new index.php at the root. But I am sure many bloggers out there have not changed the default wordpress settings. Anyways our google pagerank of the main page is now down from PR5 to PR4 and archives page has increased from PR3 to PR4!

Well we have now unchecked the canonical url options in the plugin, changed the index page to be different from the archives page and wait for Google to reindex our content and restore PR is possible. We had already set our preferred domain in Google webmaster tools earlier.

preferred domain


Considering that All in One SEO Plugin is the most popular wordpress plugin ever and is downloaded over 1.3 million time, and many WordPress bloggers host their WordPress files in alternative directories, I believe this is an important issue to address.

WordPress Plugin Lessons

So some humble suggestions for WordPress plugins developers, especially when popular plugins may effect thousands of blogs with one click –

1. Please do NOT check new options as default in upgrades.

2. It would be great if they added changelog link to WP options panel should be mandatory, especially the latest update, so bloggers can check out what are the latest major fixes out there.

It would be great if WordPress codex added a changelog to the individual plugin navigation page by default, so that users know what the latest updates are.

It would be interesting to hear the views of our learned readers, and what else could we be doing wrong to reduce our Google PR.

NOTE: All-in-One SEO Pack is an amazing and highly recommended wordpress plugin. I am not a SEO expert but the canonical url errors may have led to our PR drop, though there are hundreds of other issues that may have led to this Google PR drop, which Google best knows. Anyway it is essential to follow Google Webmaster guidelines always.

Update – I have changed the post title, which was being wrongly interpreted. Note that the plugin did what it was supposed to do and affected our site because WordPress address and Blog address are the same in our WP admin settings. So basically the plugin needs some more options for canonical url settings in with different wordpress settings. Basically those who host WordPress in an alternative directory should check the canonical options and fix them if required.

Update – Mark points to this nice video of Google engineer Matt Cutts explaining the canonical link element and SEO, which would be useful context here.

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About the Author: P Chandra is editor of QOT, one of India's earliest tech bloggers since 2004. A tech enthusiast with expertise in coding, WordPress, web tools, SEO and DIY hacks.