Can't open software-properties-gtk in Ubuntu 20.04

I can't open software-properties-gtk in Ubuntu 20.04. This the error I get:

software-properties-gtk
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 177, in activate_name_owner
    return self.get_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 361, in get_name_owner
    return self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 652, in call_blocking
    reply_message = self.send_message_with_reply_and_block(
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'com.ubuntu.SoftwareProperties': no such name

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/software-properties-gtk", line 100, in <module>
    app = SoftwarePropertiesGtk(datadir=options.data_dir, options=options, file=file)
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 208, in __init__
    proxy = bus.get_object("com.ubuntu.SoftwareProperties", "/")
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 241, in get_object
    return self.ProxyObjectClass(self, bus_name, object_path,
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 250, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 182, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 277, in start_service_by_name
    return (True, self.call_blocking(BUS_DAEMON_NAME, BUS_DAEMON_PATH,
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 652, in call_blocking
    reply_message = self.send_message_with_reply_and_block(
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.PermissionsInvalid: The permission of the setuid helper is not correct

To fix this error you have to restore setuid permission bit for relevant Dbus executable helper by using below command:

sudo chmod u+s /usr/lib/dbus-1.0/dbus-daemon-launch-helper

and then try again to launch software-properties-gtk.

Also consider to check whole filesystem for errors by fsck.