I received an error, "could not calculate upgrade"

[Wendy Wilwert]

I received an error, "could not calculate the upgrade" while trying to upgrade from Ubuntu version 12.04 LTS to v. 14.04 LTS.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.17
ProcVersionSignature: Ubuntu 3.2.0-67.101-generic 3.2.60
Uname: Linux 3.2.0-67-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: amd64
Date: Sat Aug 23 15:33:55 2014
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1408825202
 com.ubuntu.update-manager show-details true
 com.ubuntu.update-manager window-height 604
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 10.04.4 LTS "Lucid Lynx" - Release amd64 (20120214.2)
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 2014-08-23 (0 days ago)
VarLogDistupgradeTermlog: