Unhandled Exception: System.BadImageFormatException when setting up package

[Andreas Schildbach]

Binary package hint: mono

I just apt-get dist-upgraded Natty to beta1, but the upgrade process hangs at the exception I'm going to attach in a few seconds.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: mono-gac 2.6.7-5ubuntu2
ProcVersionSignature: Ubuntu 2.6.38-5.32-generic 2.6.38-rc6
Uname: Linux 2.6.38-5-generic x86_64
Architecture: amd64
Date: Fri Apr 1 17:36:29 2011
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Alpha amd64 (20100630.2)
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: mono
UpgradeStatus: Upgraded to natty on 2011-01-20 (70 days ago)