"hold prevents markGarbage..." - possible fault for not being able to upgrade to Ubuntu 16.04

[Hugo]

I followed the instructions at OMBUbuntu!
http://www.omgubuntu.co.uk/2016/04/how-to-upgrade-ubuntu-15-10-to-16-04-lts

However, the installation procedure for Ubuntu 16.04 failed after that which led me to removing all of my 3rd party sources. In doing so, I looked up the "markGarbage" error and removed any sources related to xserver. Unknowingly, it turned out to be something important so I went into Recovery mode later on and had to install xserver through there which thankfully I was able to get into my Desktop again. Now, I'm here with the same error not knowing what it is, and even questioning myself if that's even the root cause of it? Thanks for the help Ubuntu!

-Hugo

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: ubuntu-release-upgrader-core 1:15.10.14.4
ProcVersionSignature: Ubuntu 4.2.0-36.41-generic 4.2.8-ckt8
Uname: Linux 4.2.0-36-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: GNOME
Date: Sun May 15 20:03:20 2016
InstallationDate: Installed on 2015-07-27 (294 days ago)
InstallationMedia: Ubuntu-GNOME 15.04 "Vivid Vervet" - Release amd64 (20150422)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to wily on 2016-05-16 (0 days ago)
VarLogDistupgradeTermlog: