Hi! For what it’s worth, there is an existing open report in the KDE Bugtracking System about what seems like a related issue: 493153 – requestPassword: Failed to read password of "USER" because of error: 1
Does the alternative method of using the krdpserver command at the terminal also work in your case?
If you are in fact experiencing the same issue, then it may be helpful to add yourself to the CC list for that bug so that you get notified of any comments or status changes on it 