Unable to upgrade from 12.04 LTS to 14

[Jon Nichols]

Distribution upgrade could not calculate the upgrade.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.18
ProcVersionSignature: Ubuntu 3.2.0-52.78-generic 3.2.48
Uname: Linux 3.2.0-52-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.8
Architecture: amd64
Date: Mon Feb 16 15:57:47 2015
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1424123719
 com.ubuntu.update-manager show-details true
 com.ubuntu.update-manager window-height 538
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu-Server 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120817.3)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: Upgraded to precise on 2015-02-16 (0 days ago)
VarLogDistupgradeTermlog: