Propriedades do Software O GTK não abrirá

Question

Quando tento abrir o Software & amp; Atualizações não abre, então eu tentei abri-lo via terminal e esta é a saída que recebo.

software-properties-gtk
/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py:40: PyGIWarning: Gdk was imported without specifying a version first. Use gi.require_version('Gdk', '3.0') before import to ensure that the right version gets loaded.
  from gi.repository import GObject, Gdk, Gtk, Gio, GLib
/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py:40: PyGIWarning: Gtk was imported without specifying a version first. Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
  from gi.repository import GObject, Gdk, Gtk, Gio, GLib

(software-properties-gtk:7701): Gtk-WARNING **: Theme directory  of theme oxygen has no size field

Traceback (most recent call last):
  File "/usr/bin/software-properties-gtk", line 101, in <module>
    app = SoftwarePropertiesGtk(datadir=options.data_dir, options=options, file=file)
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 172, in __init__
    self.show_keys()
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 867, in show_keys
    for key in self.apt_key.list():
  File "/usr/lib/python3/dist-packages/softwareproperties/AptAuth.py", line 78, in list
    for line in p:
  File "/usr/lib/python3.5/codecs.py", line 321, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xdf in position 3914: invalid continuation byte