User Story: I want to upload an file to commons using the UploadWizard
What happens: Using a file name like: Wikidatta Flyer for Developers Part 2/2 (OUTSIDE) , the user gets an error message: "This title contains some undesirable characters. Please remove them"
The user does not know which characters are undesirable. A long time computer user might infer that it is the best to go with ASCII, but many will not.
What should happen instead: Ideally, the error message should point out the "bad" characters that were used. As a generic alternative, the error message should state which characters are not allowed.