The canonical URL is broken.
CanonicalInvalidStatus
Level
Warning
Category
SEO
Description
The page links to a canonical URL that returned an invalid status code.
Recommendation
Make sure that the canonical URL is the correct URL.
These violations are from the Bing SEO Toolkit, and are the same violations that Bing finds when crawling the internet, it is a safe bet that Google would find much the same violations.
"exactly the same as the crawler of the search engine will see it"
Date Recorded: 2011-11-07