12.04 & update-manager script error after recent update

[snowkinguk]

Good evening

I have been using 12.04 upgraded from 10.04 for a couple of weeks and everything has been working well. Yesterday evening I ran update manager (GUI) which updated a number of packages of which I am sure linux-headers was one. I was expecting a new kernel in the grub when I rebooted but nothing had changed.

I am now unable to run update-manager from the GUI or command line.

I get the following error on the command-line:

$ update-manager
Traceback (most recent call last):
File "/usr/bin/update-manager", line 33, in <module>
from UpdateManager.UpdateManager import UpdateManager
File "/usr/lib/python2.7/dist-packages/UpdateManager/UpdateManager.py", line 32, in <module>
from gi.repository import Gio
File "/usr/lib/python2.7/dist-packages/gi/importer.py", line 76, in load_module
dynamic_module._load()
File "/usr/lib/python2.7/dist-packages/gi/module.py", line 224, in _load
overrides_modules = __import__('gi.overrides', fromlist=[self._namespace])
ValueError: bad marshal data (unknown type code)

I have tried:

sudo apt-get update
sudo apt-get upgrade

Any suggestions and thank you in advance?

[snowkinguk]

Was thinking of restoring a backup image I have before the problem occurred but worried it will just happen again? Does anyone have any other suggestions?

Additional info:

ls /var/crash -l

-rw-r----- 1 [blanked-out] whoopsie 45014 May 28 19:20 _usr_bin_update-manager.1000.crash
-rw-r----- 1 [blanked-out] whoopsie 20488 May 28 19:19 _usr_lib_unity-lens-video_unity-lens-video.1000.crash
-rw-r----- 1 root whoopsie 24951 May 28 19:20 _usr_sbin_aptd.0.crash
-rw-r----- 1 [blanked-out] whoopsie 10359760 May 28 19:20 _usr_share_apport_apport-gtk.1000.crash
-rw-r----- 1 [blanked-out] whoopsie 45579 May 28 19:20 _usr_share_software-center_software-center.1000.crash

Also tried:

sudo dpkg-reconfigure -a

Online upgrade from 10.04 -> 12.04 ; ran fine for a couple of weeks until some updates were installed recently by update-manager

Thanks