cannot upgrade from 15.10 to 16.04

[sebastian ovide]

sudo update-manager -d

says

Could not determine 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.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: ubuntu-release-upgrader-core 1:15.10.14.4
ProcVersionSignature: Ubuntu 4.2.0-38.45-generic 4.2.8-ckt10
Uname: Linux 4.2.0-38-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Fri Jun 17 16:21:27 2016
InstallationDate: Installed on 2014-03-09 (830 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to wily on 2016-06-17 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

You seem to have a lot of packages on hold which is causing the release upgrader to fail to calculate the upgrade. The files on hold can be seen in your VarLogDistupgradeAptlog file.

[Launchpad Janitor (janitor)]

[Expired for ubuntu-release-upgrader (Ubuntu) because there has been no activity for 60 days.]