Failure to upgrade frpm 13.10 to 14.4

[Simon Curry]

Currently using : Ubuntu 13.10

Was offered upgrade option to 14.4 after responding to software center prompt to install new patch.
Accepted offer.
Watched preparation.
Got a message about 3rd Party software.

Finally got message:

An unresolvable problem occurred while calculating the upgrade.

 This can be caused by:
 * Upgrading to a pre-release version of Ubuntu
 * Running the current pre-release version of Ubuntu
 * Unofficial software packages not provided by Ubuntu

If none of this applies, then please report this bug using the command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: ubuntu-release-upgrader-core 1:0.205.6
ProcVersionSignature: Ubuntu 3.11.0-20.35-generic 3.11.10.6
Uname: Linux 3.11.0-20-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
CrashDB: ubuntu
Date: Thu May 8 00:18:42 2014
MarkForUpload: True
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to saucy on 2014-05-08 (0 days ago)
VarLogDistupgradeTermlog: