Ubuntu – Software & Updates crashes and will not open

I am unable to open the Software & Updates configuration window in System Settings. The best I have been able to do to understand what is going on is the following output after opening System Settings from terminal and clicking Software & Updates:

$ sudo unity-control-center 
/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
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 175, 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
    's', (bus_name,), **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
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 101, in <module>
    app = SoftwarePropertiesGtk(datadir=options.data_dir, options=options, file=file)
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 141, in __init__
    proxy = bus.get_object("com.ubuntu.SoftwareProperties", "/")
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed: Failed to execute program com.ubuntu.SoftwareProperties: Permission denied

The same error occurs when executing software-properties-gtk (because AFAIK, it is one and the same).

Software Updater has been having some similar issues, and often crashes with this error:

$ sudo update-manager 
/usr/bin/update-manager:28: 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 Gtk
/usr/lib/python3/dist-packages/UpdateManager/UnitySupport.py:29: PyGIWarning: Dbusmenu was imported without specifying a version first. Use gi.require_version('Dbusmenu', '0.4') before import to ensure that the right version gets loaded.
  from gi.repository import Dbusmenu, Unity
/usr/lib/python3/dist-packages/UpdateManager/UnitySupport.py:29: PyGIWarning: Unity was imported without specifying a version first. Use gi.require_version('Unity', '7.0') before import to ensure that the right version gets loaded.
  from gi.repository import Dbusmenu, Unity
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 175, 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
    's', (bus_name,), **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'org.debian.apt': no such name

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/defer/__init__.py", line 487, in _inline_callbacks
    result = gen.send(result)
  File "/usr/lib/python3/dist-packages/aptdaemon/client.py", line 1613, in _run_transaction_helper
    daemon = get_aptdaemon(self.bus)
  File "/usr/lib/python3/dist-packages/aptdaemon/client.py", line 1701, in get_aptdaemon
    False),
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed: Failed to execute program org.debian.apt: Permission denied
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 175, 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
    's', (bus_name,), **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'org.debian.apt': no such name

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/defer/__init__.py", line 487, in _inline_callbacks
    result = gen.send(result)
  File "/usr/lib/python3/dist-packages/aptdaemon/client.py", line 1613, in _run_transaction_helper
    daemon = get_aptdaemon(self.bus)
  File "/usr/lib/python3/dist-packages/aptdaemon/client.py", line 1701, in get_aptdaemon
    False),
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed: Failed to execute program org.debian.apt: Permission denied
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 175, 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
    's', (bus_name,), **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'org.debian.apt': no such name

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/aptdaemon/client.py", line 1584, in on_error
    error.raise_exception()
  File "/usr/lib/python3/dist-packages/defer/__init__.py", line 130, in raise_exception
    raise self.value.with_traceback(self.traceback)
  File "/usr/lib/python3/dist-packages/defer/__init__.py", line 487, in _inline_callbacks
    result = gen.send(result)
  File "/usr/lib/python3/dist-packages/aptdaemon/client.py", line 1613, in _run_transaction_helper
    daemon = get_aptdaemon(self.bus)
  File "/usr/lib/python3/dist-packages/aptdaemon/client.py", line 1701, in get_aptdaemon
    False),
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed: Failed to execute program org.debian.apt: Permission denied
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 175, 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
    's', (bus_name,), **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'org.debian.apt': no such name

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/defer/__init__.py", line 483, in _inline_callbacks
    result = gen.throw(excep)
  File "/usr/lib/python3/dist-packages/UpdateManager/backend/InstallBackendAptdaemon.py", line 65, in update
    trans = yield self.client.update_cache(defer=True)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed: Failed to execute program org.debian.apt: Permission denied

Overall, it seems like Python and GTK are vomiting all over the place, but I don't know how to fix it.

There have been various other related issues such as being unable to install packages from the Software Center, or a variety of crashes from trying to update on startup.

I have already tried reinstalling software center with no luck, and am afraid to attempt this solution as the people in the comments say it's a bad idea. I have come here after finding a lack of answers everywhere else.

Edit:

Interestingly, I've encountered another error that is very similar in nvidia-settings. Error output is shown below when trying to save xorg.conf settings.

$ sudo nvidia-settings ** Message: PRIME: No offloading required. Abort
** Message: PRIME: is it supported? no
Package xorg-server was not found in the pkg-config search path.
Perhaps you should add the directory containing `xorg-server.pc'
to the PKG_CONFIG_PATH environment variable
No package 'xorg-server' found
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 175, 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
    's', (bus_name,), **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'com.ubuntu.ScreenResolution.Mechanism': no such name

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/share/screen-resolution-extra/nvidia-polkit.py", line 75, in <module>
    operation_status = main(options)
  File "/usr/share/screen-resolution-extra/nvidia-polkit.py", line 42, in main
    conf = get_xkit_service()
  File "/usr/share/screen-resolution-extra/nvidia-polkit.py", line 33, in get_xkit_service
    service_object = dbus.SystemBus().get_object(SERVICE_NAME, OBJECT_PATH)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed: Failed to execute program com.ubuntu.ScreenResolution.Mechanism: Permission denied

ERROR: Unable to open X config file '/etc/X11/xorg.conf' for writing.

And later, when trying to update pip, I find this error:

$ sudo pip install --upgrade pip
The directory '/home/max/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.