Came across this topic link from an archive at en:Talk:Flow. Whatever that topic was, it appears to have gone walkies. If it's been deleted, a better error message should be on display; if it's been moved(?), the reader should be taken there.
Topic on Talk:Structured Discussions
Scott: Here's "Topics with recent posts". The oldstyle links broke yesterday, and that's bugzilla:68224 (and patch at review). (Sidenote: They're working on some improved URLs, with this short "topic:uuid" basis, but suffixed with humanreadable info, ala reddit/etc. :)