Unable to upgrade from 12.04 to 14.04

[Paul Guenther]

Unable to upgrade from 12.04 to 14.04.

Error message says "Unable to calculate changes, may be due to pre-release versions or unofficial software packages."

Neither should be the case in this instance.

Thanks

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.21
ProcVersionSignature: Ubuntu 3.2.0-119.162-generic-pae 3.2.79
Uname: Linux 3.2.0-119-generic-pae i686
ApportVersion: 2.0.1-0ubuntu17.15
Architecture: i386
Date: Mon Dec 19 15:58:57 2016
EcryptfsInUse: Yes
GsettingsChanges:
 com.ubuntu.update-manager check-new-release-ignore 'trusty'
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1482180481
 com.ubuntu.update-manager window-height 535
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release i386 (20120423)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 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 2016-12-19 (0 days ago)

[Launchpad Janitor (janitor)]

[Expired for update-manager (Ubuntu) because there has been no activity for 60 days.]