So this seems to happen when starting software-properties-dbus, then adding a new apt source; the D-BUS backend does not know about it yet, but the frontend does, so the backend doesn't find the Source for the corresponding string when trying to disable it.
So this seems to happen when starting software- properties- dbus, then adding a new apt source; the D-BUS backend does not know about it yet, but the frontend does, so the backend doesn't find the Source for the corresponding string when trying to disable it.