KPackageKit shows "unexpected error" (german "unerwarteter Fehler") when reloading software updates

[Lotharster]

When the Automatic software update checks for new updates, or when the update check is performed manually in KPackageKit,
an error is displayed: "Es ist ein unerwarteter Fehler aufgetreten.
Bitte melden Sie das Problem mit der Fehlerbeschreibung."
in English approx: "An unexpected error has occured. Please report the problem with the error description."

The following detailed error log is provided:

Error Type:
Error Value: coercing to Unicode: need string or buffer, exceptions.SystemError found
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 2216, in
main()
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 2213, in main
run(args, options.single)
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 2175, in run
backend.dispatcher(args)
File : /usr/lib/python2.6/dist-packages/packagekit/backend.py, line 699, in dispatcher
self.dispatch_command(args[0], args[1:])
File : /usr/lib/python2.6/dist-packages/packagekit/backend.py, line 606, in dispatch_command
self.refresh_cache(force)
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 202, in _locked_cache
func(*args, **kwargs)
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 1498, in refresh_cache
format_string(error.message))
File : /usr/lib/python2.6/dist-packages/packagekit/backend.py, line 723, in format_string
txt = unicode(text, encoding, errors='replace')

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: kpackagekit 0.5.4-0ubuntu4.3
ProcVersionSignature: Ubuntu 2.6.32-41.94-generic 2.6.32.59+drm33.24
Uname: Linux 2.6.32-41-generic x86_64
Architecture: amd64
Date: Wed Jul 25 20:50:19 2012
InstallationMedia: Kubuntu 10.04.4 LTS "Lucid Lynx" - Release amd64 (20120214.1)
ProcEnviron:
 LANGUAGE=
 LANG=de_DE.utf8
 SHELL=/bin/bash
SourcePackage: kpackagekit

[Daniel Nicoletti (dantti)]

This is not KPackageKit bug, it's a known packagekit-backend-apt bug which will NEVER be fixed...
The apt backend had too many bugs so I wrote a backend called aptcc (package packagekit-backend-aptcc) which is now the official apt backend, so please use it and update to a more recent distro release.
Best