Comment 2 for bug 1525635

Please install one of the following meta packages, probably ubuntu-desktop, for the upgrade to get further along.

2015-12-13 11:45:56,040 DEBUG none of the '['ubuntu-desktop', 'kubuntu-desktop', 'xubuntu-core', 'xubuntu-desktop', 'ubuntustudio-desktop', 'mythbuntu-desktop', 'kubuntu-netbook', 'lubuntu-core', 'lubuntu-desktop', 'ubuntu-gnome-desktop']' meta-pkgs installed
2015-12-13 11:45:56,040 DEBUG guessing 'ubuntu-desktop' as missing meta-pkg
2015-12-13 11:45:57,188 ERROR failed to mark 'ubuntu-desktop' for install (E:Unable to correct problems, you have held broken packages.)
2015-12-13 11:45:57,328 DEBUG blacklist expr 'unity$' matches 'unity'
2015-12-13 11:45:57,328 DEBUG The package 'unity' is marked for removal but it's in the removal blacklist
2015-12-13 11:45:57,395 ERROR Dist-upgrade failed: 'The package 'unity' is marked for removal but it is in the removal blacklist.'