dist-upgrade failed from 16.04.2 to 16.10

[Francesco Agozzino]

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

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.21
ProcVersionSignature: Ubuntu 4.4.0-67.88-generic 4.4.49
Uname: Linux 4.4.0-67-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: GNOME
Date: Wed Mar 15 14:25:20 2017
InstallationDate: Installed on 2014-11-04 (861 days ago)
InstallationMedia: Ubuntu-GNOME 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to xenial on 2017-03-15 (0 days ago)
mtime.conffile..etc.update-manager.release-upgrades: 2017-03-15T14:23:07.956581