Traceback (most recent call last):
  File "/usr/bin/software-properties-gtk", line 103, in <module>
    app = SoftwarePropertiesGtk(datadir=options.data_dir, options=options, file=file)
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 160, in __init__
    self.apt_cache = apt.Cache()
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 102, in __init__
    self.open(progress)
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 149, in open
    self._list.read_main_list()
SystemError: E:Malformed line 61 in source list /etc/apt/sources.list (dist parse)