You seem to have multiple metapackages installed which creates a difficult situation for the release upgrader. I suggest choosing which ever environment you are using.
2016-09-07 22:24:26,566 DEBUG Marking 'kubuntu-desktop' for upgrade
2016-09-07 22:24:27,462 DEBUG Marking 'mythbuntu-desktop' for upgrade
2016-09-07 22:24:29,703 DEBUG metapkg 'kubuntu-desktop' installed but marked_delete
2016-09-07 22:24:29,704 DEBUG metapkg 'kubuntu-desktop' installed but marked_delete
2016-09-07 22:24:30,151 DEBUG blacklist expr 'kubuntu-desktop' matches 'kubuntu-desktop'
2016-09-07 22:24:30,152 DEBUG The package 'kubuntu-desktop' is marked for removal but it's in the removal blacklist
2016-09-07 22:24:30,209 ERROR Dist-upgrade failed: 'The package 'kubuntu-desktop' is marked for removal but it is in the removal blacklist.'
You seem to have multiple metapackages installed which creates a difficult situation for the release upgrader. I suggest choosing which ever environment you are using.
2016-09-07 22:24:26,566 DEBUG Marking 'kubuntu-desktop' for upgrade
2016-09-07 22:24:27,462 DEBUG Marking 'mythbuntu-desktop' for upgrade
2016-09-07 22:24:29,703 DEBUG metapkg 'kubuntu-desktop' installed but marked_delete
2016-09-07 22:24:29,704 DEBUG metapkg 'kubuntu-desktop' installed but marked_delete
2016-09-07 22:24:30,151 DEBUG blacklist expr 'kubuntu-desktop' matches 'kubuntu-desktop'
2016-09-07 22:24:30,152 DEBUG The package 'kubuntu-desktop' is marked for removal but it's in the removal blacklist
2016-09-07 22:24:30,209 ERROR Dist-upgrade failed: 'The package 'kubuntu-desktop' is marked for removal but it is in the removal blacklist.'