In ancient MS-DOS times a nice tool told me:
User Error! Please replace user and try again!
This is not only a good error message, it is a complete help system!

(1) Error occured. (mhmhm)
(2) Reason: Clearly stated: "User" error. No discussion needed.
(3) And they told me in 6 words (incl. "please") how to prevent/fix the error (or to have a workaround at least).

Cool!