Could not upgrade from 12.04 to 14.04: upgrade-manager should be deleted, but is blacklisted.

[volldillo]

Description: Ubuntu 12.04.5 LTS
Release: 12.04
(kubuntu)
ProcVersionSignature: Ubuntu 3.2.0-70.105-generic 3.2.63
Tags: precise dist-upgrade
Uname: Linux 3.2.0-70-generic i686

Package: update-manager (not installed)
"blacklist expr 'update-manager' matches 'update-manager-kde'
The package 'update-manager-kde' is marked for removal but it's in the removal blacklist"

I expected to upgrade to kubuntu 14.04, but the script stopped with exit code "1" after the packages were downloaded and the installation should start.

Generating the error report chrashes too:

> ubuntu-bug ubuntu-release-upgrader-core
ERROR: hook /usr/share/apport/general-hooks/cloud_archive.py crashed:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/apport/report.py", line 719, in add_hooks_info
    symb['add_info'](self, ui)
  File "/usr/share/apport/general-hooks/cloud_archive.py", line 18, in add_info
    if '~cloud' in packaging.get_version(package) and \
  File "/usr/lib/python2.7/dist-packages/apport/packaging_impl.py", line 95, in get_version
    raise ValueError('package does not exist')
ValueError: package does not exist
python: ../../src/xcb_io.c:529: _XAllocID: Zusicherung »ret != inval_id« nicht erfüllt.
KCrash: Application '' crashing...
KCrash: Attempting to start /usr/lib/kde4/libexec/drkonqi from kdeinit
sock_file=/home/andreas/.kde/socket-poincare/kdeinit4__0
QSocketNotifier: Invalid socket 38 and type 'Read', disabling...