can't upgrade version 12.04 to 14.04

[benez9]

update manager unables to upgrade to 14.04 from 12.04

the message is
* Upgrading to a pre-release version of Ubuntu
 * Running the current pre-release version of Ubuntu
 * Unofficial software packages not provided by Ubuntu

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.19
ProcVersionSignature: Ubuntu 3.13.0-79.123~precise1-generic 3.13.11-ckt33
Uname: Linux 3.13.0-79-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.13
Architecture: amd64
Date: Tue Mar 1 09:49:27 2016
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: Upgraded to precise on 2016-03-01 (0 days ago)
VarLogDistupgradeTermlog:

[Ubuntu Foundations Team Bug Bot (crichton)]

You seem to have installed the cinnamon package on Ubuntu 13.10. Unfortunately, that package is not available yet for 14.04. To upgrade to Ubuntu 14.04 LTS you'll need to either wait for a fix for cinnamon to be available or uninstall the package and then upgrade.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]