Canonical to a non-indexable URL
IssueHigh priority
Pages whose canonical points at an address that cannot be indexed: one that is blocked, redirects, or is not there.
Why it matters
The page gives up its place to one that cannot take it, so neither is indexed and the content disappears from search.
How to fix it
Point the canonical at an address that answers 200 and is indexable, or make the target indexable.
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.