I got this error as well while performing a distribution upgrade. I'm running Gutsy 7.10. The error message also told me to include the file which I have attached.
** Attachment added: "apt.log" http://launchpadlibrarian.net/12236756/apt.log -- update-manager: A unresolvable problem occurred while calculating the upgrade. https://bugs.launchpad.net/bugs/79252 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
