Query “Search Console” suddenly started returning a very specific (and for that matter very wrong) canonical URL containing the following parameter &siteUrl=ftp://geograph.org.uk/
Full URL: https://www.google.com/webmasters/tools/home?hl=en&siteUrl=ftp://geograph.org.uk/
Why did Google suddenly switch away from the correct URL? Well ironically the tool whose role is in part to alert webmasters of canonicalisation issues hasn’t canonicalised its own URLs.
In this case there is one significant instance of the URL on Google’s forums back from February 2014:
(I’m probably not helping things by linking to it, just I linked to the wrong canonical URL.)
There is also a second instances of this URL in Google’s index for Search Console site query which confirms that Google got hold of those URLs from the forum page.
That’s not the strange part however. Lack of canonical URL can cause confusion in search results as Google isn’t sure which version is more suitable return in results. This is typically ironed out with other signals, links for example. If one page has more inbound links it’s more likely to be more relevant. Similarly Google could simply observe user behaviour signals to understand page popularity and relevance. So here is the unusual part. We’re looking at a low volume of links (all rel=”nofollow”) and the post is old, so QDF factors cannot be considered either.
Another observation is that the correct URL is returned for “Google Search Console” but not for “Search Console“.
I’ve reached out to Google for comments.