When I was trying to post this topic, I kept getting tags: invalid tags. Turns out, you can't use a dash in a tag (in my case, it is needed for the double surname Rockall-Schmidt). A more user-friendly way to report this would be a message like

tags: invalid character “-”; valid characters are letters, numbers, and spaces

(And, on a related note, I think banning a dash from tags is kind of restricting, although I see the point if you want to use it as a minus sign to exclude tags.)