Traceback (most recent call last):
  File "/usr/share/software-center/softwarecenter/ui/gtk3/app.py", line 1180, in show_lobby
    self.view_manager.set_active_view(ViewPages.AVAILABLE)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/session/viewmanager.py", line 125, in set_active_view
    view_widget.init_view()
  File "/usr/share/software-center/softwarecenter/ui/gtk3/panes/availablepane.py", line 131, in init_view
    self.apps_filter)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/views/catview_gtk.py", line 226, in __init__
    self.build(desktopdir)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/views/catview_gtk.py", line 475, in build
    self.categories = self.parse_applications_menu(desktopdir)
  File "/usr/share/software-center/softwarecenter/db/categories.py", line 116, in parse_applications_menu
    category = self._parse_menu_tag(child)
  File "/usr/share/software-center/softwarecenter/db/categories.py", line 270, in _parse_menu_tag
    (untranslated_name, name, gettext_domain, icon) = self._parse_directory_tag(element)
TypeError: 'NoneType' object is not iterable