Не удалось обновить Kubuntu 16.04 (проблема с xserver-xorg-video-all?) [Дубликат]

Я пытаюсь обновить свой компьютер Kubuntu Wily 15.10, но это не удается.

Я делаю это:

$ sudo do-release-upgrade -m desktop

Вот что я получаю:

Calculating the changes

Could not calculate the upgrade 

An unresolvable problem occurred while calculating the upgrade. 

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 ubuntu-release-upgrader-core' in a terminal. 

Я нашел это на /var/log/dist-upgrade/main.log :

2016-04-29 10:29:09,024 DEBUG need_server_mode(): run in 'desktop' mode, (because of key deps for 'kubuntu-desktop')
2016-04-29 10:29:16,112 DEBUG Installing 'xserver-xorg-video-all' (Distro KeepInstalledPkgs rule)
2016-04-29 10:29:16,559 ERROR Dist-upgrade failed: 'E:Unable to correct problems, you have held broken packages.'
2016-04-29 10:29:16,560 DEBUG abort called
2016-04-29 10:29:16,576 DEBUG openCache()
2016-04-29 10:29:16,576 DEBUG failed to SystemUnLock() (E:Not locked) 
2016-04-29 10:29:20,464 DEBUG /openCache(), new cache size 78719
2016-04-29 10:29:20,464 DEBUG enabling apt cron job

Что я могу делать?