Traceback (most recent call last):
  File "/usr/bin/update-manager", line 108, in <module>
    app = UpdateManager(data_dir, options)
  File "/usr/lib/python2.7/dist-packages/UpdateManager/UpdateManager.py", line 175, in __init__
    self.setupDbus()
  File "/usr/lib/python2.7/dist-packages/UpdateManager/UpdateManager.py", line 360, in setupDbus
    self.dbusController = UpdateManagerDbusController(self, bus_name)
  File "/usr/lib/python2.7/dist-packages/UpdateManager/UpdateManager.py", line 132, in __init__
    self.alert_watcher = AlertWatcher ()
  File "/usr/lib/python2.7/dist-packages/UpdateManager/Core/AlertWatcher.py", line 45, in __init__
    self.bus = dbus.Bus(dbus.Bus.TYPE_SYSTEM)
  File "/usr/lib/python2.7/dist-packages/dbus/_dbus.py", line 108, in __new__
    bus = BusConnection.__new__(subclass, bus_type, mainloop=mainloop)
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 125, in __new__
    bus = cls._new_for_bus(address_or_type, mainloop=mainloop)
DBusException: org.freedesktop.DBus.Error.NoServer: Failed to connect to socket /var/run/dbus/system_bus_socket: Connexion refusée