Links used to download privately generated PDF files throw 404 errors when visited later. Example:
http://hu.wikipedia.org/w/index.php?title=Speci%C3%A1lis:K%C3%B6nyv&bookcmd=download&collection_id=3a9b478af26ea6a8&writer=rl&return_to=T%C3%B6r%C3%B6korsz%C3%A1g&uselang=en
Such links should fail in a user-friendlier way, with an error message saying the link has expired and maybe giving some pointers on how to generate publicly visible collections.
Version: unspecified
Severity: minor