Answers with and without a trailing slash
WarningMedium priority
Pages of this site that answer both at their address and at it with the trailing slash added or taken away.
Why it matters
The two are different addresses serving one page, so its links and its place in search results are split between them and it is crawled twice. A canonical helps, but only a redirect settles it.
How to fix it
Choose one form for the whole site, redirect the other to it with a 301, and link only to the one that stays.
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.