Wikimedia Bugzilla is closed!

When the {{#special:}} parser function is called with an unknown special page name, it currently returns “No such special page” ({{int:nosuchspecialpage}}), i.e. a user-readable textual message where a page name is expected. (Or, in other words, instead of a title of a page in NS_SPECIAL, it returns a title in NS_MAIN.) This is especially strange in the {{#speciale:}} variant (which returns “No_such_special_page”).

This is surprising behavior. It would be more logical to just return the requested title (we are unable to return the _localized_ title of the special page, so just use the given one). (Or, an alternative solution would be to always return Special:Badtitle.)