I think I found the reason for the error. I was missing the plasma-widget-network-manager package. But that leads to another problem: Why was the widget listed as available to be added if the package was missing?
-- Jaunty: KDE4: Network manager widget kills plasma https://bugs.launchpad.net/bugs/412793 You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to knetworkmanager in ubuntu. -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
