While trying to do a “do-release-upgrade”, to upgrade to Ubuntu Precise, I encountered a error that Google did not find a satisfactory answer for:
An unresolvable problem occurred while calculating the upgrade: E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages. 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 using the command 'ubuntu-bug update-manager' in a terminal.
The problem was I had some packages installed that had no upgrade path, that is, are not available in Precise. To debug this I looked in the
/var/log/dist-upgrade/apt.log file, and it identifies the packages that were “broken”. I just had to “apt-get remove” them, do the release upgrade, and afterwards I could reinstall them.