Comment 9 for bug 219531

I was trying to upgrade from 7.10 Ubuntu following a CD install while under XFCE. (I installed xubuntu-desktop and used synaptic-manager to mark packages for upgrade)

I was given the error message:
Could not calculate the upgrade

A unresolvable problem occurred while calculating the upgrade.

 This can be caused by:
 * Upgrading to a pre-release version of Ubuntu
 * Running the current pre-release version of Ubuntu
 * Unofficial software packages not provided by Ubuntu

If none of this applies, then please report this bug against the 'update-manager' package and include the files in /var/log/dist-upgrade/ in the bugreport.