Tried to upgrade to 17.04 from 16.10. It is not a clean installation and had been upgraded several times before, so maybe there is the reason. I'll try my best to figure it out.

[Fabian Gumz]

1
Description: Ubuntu 16.10
Release: 16.10

2
Unable to locate package pkgname
No wonder, tried a distribution update

3
The updater should have updated my system automatically from 16.10 to 17.04

4
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.

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: ubuntu-release-upgrader-core 1:16.10.10
ProcVersionSignature: Ubuntu 4.8.0-49.52-generic 4.8.17
Uname: Linux 4.8.0-49-generic x86_64
ApportVersion: 2.20.3-0ubuntu8.2
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: GNOME
Date: Sat Apr 22 00:58:49 2017
InstallationDate: Installed on 2015-03-17 (766 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to yakkety on 2017-04-21 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

Reviewing the files from your upgrade attempt you seem to have enabled a PPA that provides Xorg packages. This will prevent the upgrade as that PPA contains different versions of packages essential to Ubuntu. The page, https://launchpad.net/~xorg-edgers/+archive/ppa, contains details on to how to revert to the official Xorg packages for the xorg-edgers PPA. Instructions for reverting to official Xorg packages should be similar for the PPA that you have enabled.