Board Thread:Support Requests - Designing Your Wikia/@comment-27384943-20160402221824/@comment-4970747-20160402222526

Pages with the prefix "Special" are managed by the software, and are therefore already created. You also cannot create a Special page, or else it will throw you an error like the one you've received. Try just linking to the page, searching for it, or looking for it in the Admin Dashboard.