upgrader fails to upgrade from14.04 to 16.04. Could not calculate the upgrade error msg.

[Andreas Bang]

I get message:

Could not calculate the upgrade

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.

i am just trying to upgrade from 14.04 to 16.04. My other laptop worked just fine, but tjis laptop using Lenovo P50s fails with the message above.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.9
ProcVersionSignature: Ubuntu 4.2.0-27.32~14.04.1-generic 4.2.8-ckt1
Uname: Linux 4.2.0-27-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.23
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: KDE
Date: Wed Dec 21 12:53:42 2016
InstallationDate: Installed on 2016-08-13 (130 days ago)
InstallationMedia: Ubuntu 14.04.4 LTS "Trusty Tahr" - Release amd64 (20160217.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2016-12-21 (0 days ago)
VarLogDistupgradeTermlog: