update from 14.04 to 16.04

[Alvaro kun]

No se ha podido calcular la actualización

Ha ocurrido un problema mientras se calculaba la actualización.

 Eso se ha podido causar por:
 * Actualizar a una versión de Ubuntu aún no publicada
 * Estar ejecutando la versión actual, aún no publicada, de Ubuntu
 * Paquetes no oficiales de software no proporcionados por Ubuntu

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.8
ProcVersionSignature: Ubuntu 3.13.0-86.131-generic 3.13.11-ckt39
Uname: Linux 3.13.0-86-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.20
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Sat May 21 13:28:06 2016
InstallationDate: Installed on 2013-10-24 (940 days ago)
InstallationMedia: This
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2016-05-21 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

Reviewing the files from your upgrade attempt you seem to have enabled a PPA that provides Xorg packages. This will prevent the upgrade as that PPA contains different versions of packages essential to Ubuntu. The page, https://launchpad.net/~xorg-edgers/+archive/ppa, contains details on to how to revert to the official Xorg packages for the xorg-edgers PPA. Instructions for reverting to official Xorg packages should be similar for the PPA that you have enabled.