kpackagekit cannot update anymore after first upgrade

On the first package update (karmik update 4) with kpackage kit , the update aborted unexpectedly.
when further update were executed , the following messages appears :

Error Type: Error Value: 'PackageKitCache' object has no attribute '_dict' File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 1966, in main() File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 1963, in main run(args, options.single) File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 1925, in run backend.dispatcher(args) File : /usr/lib/python2.6/dist-packages/packagekit/backend.py, line 632, in dispatcher self.dispatch_command(args[0], args[1:]) File : /usr/lib/python2.6/dist-packages/packagekit/backend.py, line 540, in dispatch_command self.get_updates(filters) File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 653, in get_updates for pkg in self._cache.getChanges(): File : /usr/lib/python2.6/dist-packages/apt/cache.py, line 164, in getChanges for p in self: File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 196, in __iter__ for pkgname in sorted(self._dict.keys()):

when reporting bug via kpackagekit help menu, a windows popup saying "invalid problem; Package 3763 does not exist" and the "collecting problem information" windows is collecting problems indefinitely.

Description: Ubuntu karmic (development branch)
Release: 9.10

kpackagekit:
  Installed: 0.4.2-0ubuntu2
  Candidate: 0.4.2-0ubuntu2
  Version table:
 *** 0.4.2-0ubuntu2 0
        500 http://be.archive.ubuntu.com karmic/main Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
Architecture: i386
Date: Tue Aug 25 07:38:04 2009
DistroRelease: Ubuntu 9.10
Package: kpackagekit 0.4.2-0ubuntu2
ProcEnviron:
 SHELL=/bin/bash
 LANG=en_US.UTF-8
 LANGUAGE=
ProcVersionSignature: Ubuntu 2.6.31-6.26-generic
SourcePackage: kpackagekit
Uname: Linux 2.6.31-6-generic i686