Some combination of fiddling with the preferred repository, removing the kubuntu-desktop metapackage, and running a plain update-manager got past the error. Best guess: changing the repository.
** Changed in: update-manager (Ubuntu) Status: Incomplete => Fix Released -- update-manager -d unable to compute upgrade from 10.04 to 10.10 beta https://bugs.launchpad.net/bugs/631978 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