update to ubuntu 15 failed..

[robert rottermann]

Hi there,

I tried to upgrade to the newest ubuntu version.
The upgrade process stopped in the middle.
Now after rebooting the computer an attempt to do any cleanup or upgrade results 
in the following:
what can I do?
thanks
robert
ps: I messed with python before ..

  No apport report written because the error message indicates its a followup 
error from a previous failure.
                                                           Errors were 
encountered while processing:
  update-notifier-common
  update-notifier
  ubuntu-desktop
E: Sub-process /usr/bin/dpkg returned an error code (1)
root at chrissy:/home/robert# apt-get autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
3 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up update-notifier-common (3.160) ...
Traceback (most recent call last):
   File "/usr/lib/update-notifier/package-data-downloader", line 24, in <module>
     import debian.deb822
ImportError: No module named debian.deb822
dpkg: error processing package update-notifier-common (--configure):
  subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of update-notifier:
  update-notifier depends on update-notifier-common (= 3.160); however:
   Package update-notifier-common is not configured yet.

dpkg: error processing package update-notifier (--configure):
  dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of ubuntu-desktop:
  ubuntu-desktop depends on update-notifier; however:
   Package update-notifier is not configured yet.

dpkg: error processing package ubuntu-desktop (--configure):
  dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup 
error from a previous failure.
No apport report written because the error message indicates its a followup 
error from a previous failure.
                                                           Errors were 
encountered while processing:
  update-notifier-common
  update-notifier
  ubuntu-desktop
E: Sub-process /usr/bin/dpkg returned an error code (1)