I can not update the version 12:04 to 14:04

[dijom]

Não Foi possível calcular a atulização

An uresolvable problem occured while calculating the upgrade.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.19
ProcVersionSignature: Ubuntu 3.2.0-83.120-generic-pae 3.2.68
Uname: Linux 3.2.0-83-generic-pae i686
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu17.8
Architecture: i386
Date: Tue May 12 20:28:02 2015
GsettingsChanges:
 com.ubuntu.update-manager launch-time 1431177767
 com.ubuntu.update-manager window-height 500
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release i386 (20120817.3)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=pt_BR:pt:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=pt_BR.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: Upgraded to precise on 2015-05-12 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

From VarLogDistupgradeMainlog.txt:

2015-05-12 20:26:00,297 DEBUG Marking 'ubuntu-desktop' for upgrade
2015-05-12 20:26:01,609 WARNING Can't mark 'ubuntu-desktop' for upgrade (E:Impossível corrigir problemas, você manteve (hold) pacotes quebrados.)
2015-05-12 20:26:01,738 DEBUG blacklist expr 'ubuntu-minimal' matches 'ubuntu-minimal'
2015-05-12 20:26:01,739 DEBUG The package 'ubuntu-minimal' is marked for removal but it's in the removal blacklist

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.