The CUPS daemon is crucial for the KDE printer settings apps. So if it isn't running I would expect a sane error message to the user, which would point him in the right direction. Reproducible: Always Steps to Reproduce: 1. End CUPS daemon 2. Open System settings - Printers Actual Results: Mysterious error message: "Invalid Argument" Expected Results: Sane error message, i.e. "Couldn't connect to CUPS service.", etc...
@Richard , when you move a report to a different product, remember to select the "Reset Assignee to default " option.
*** This bug has been marked as a duplicate of bug 316792 ***