Canonical to an error
IssueHigh priority
Pages whose canonical points at an address that answered with an error, or did not answer.
Why it matters
The page names a replacement that does not exist, which is the clearest way to lose it from search results.
How to fix it
Correct the address, or restore whatever used to be there.
Skitter runs this check on every crawl, and lists each page it finds with the evidence: the header, the tag or the link that gave it away.