Remember that possible Google search ranking algorithm update from September 23rd? As I mentioned in my weekly video this Friday, some felt it may have been caused by a canonical bug with Google search. I wanted to share more around that topic before I go offline tonight for Yom Kippur, since I am not posting anything tomorrow.

In short, what happened on the 23rd and 24th of September may have been related to a Google bug related to which URLs the search engine is selecting as the canonical URL. Basically, Google seemed to have swapped out one URL with another unrelated URL for many web sites. This can 100% be the reason for the fluctuations you see in the search results and the tracking tools. It can also be why so many people are thinking there was an update and their site may have been hit because URLs that once ranked, no longer do rank.

I had numerous people email me and reach out to me about this issue.

Divyanka posted about this super early on based on some of the comments on my story and what he spotted:

Here is a set of great tweets from Glenn Gabe documenting some of this:

Here is another:

Some of the folks in Black Hat World picked this up too.

And this BHW thread:

A WebmasterWorld thread is talking just about this now, including a ton of posts on this from the ongoing WebmasterWorld thread:

Some threads at Google Webmaster Help Forums:

Google has had issues like this before – back in April 2019 Google has a canonical URL bug, here is when Google confirmed that back then:

I will dig in more hopefully on Tuesday after Yom Kippur.

So far Google has not confirmed any issues with me or publically.

Forum discussion at Black Hat World, WebmasterWorld and Google Webmaster Help Forums.

Update: Give Google examples over here.

Update 2: Google has now confirmed this as an indexing issue with mobile-indexing and canonicalization.