Release Upgrader unable to determine upgrade

[Laurie]

I previously submitted https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1782849 and was advised by https://launchpad.net/~brian-murray that bug was a duplicate of https://bugs.launchpad.net/bugs/1069133 and that the reason I was experiencing the issue was because I was using the oibaf PPA that includes drivers that have higher version numbers than those provided by the upgrade.

I purged the oibaf PPA from my system and downgraded drivers, however I'm still experiencing the same problem. The upgrade won't work because it's unable to determine the upgrade. Can someone please let me know exactly which repos I need to re-enable and purge so I can get this update sorted. Thanks in advance.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: ubuntu-release-upgrader-core 1:17.10.11
ProcVersionSignature: Ubuntu 4.13.0-46.51-generic 4.13.16
Uname: Linux 4.13.0-46-generic x86_64
NonfreeKernelModules: talpa_vfshook talpa_pedconnector talpa_pedevice talpa_vcdevice talpa_core talpa_linux talpa_syscallhook nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.7-0ubuntu3.9
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: KDE
Date: Tue Jul 24 20:06:26 2018
InstallationDate: Installed on 2017-11-08 (258 days ago)
InstallationMedia: Kubuntu 17.10 "Artful Aardvark" - Release amd64 (20171017.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to artful on 2018-07-25 (0 days ago)
VarLogDistupgradeTermlog:

[Laurie (ljl069)]

I do have an NVidia GPU, and am using the drivers from https://launchpad.net/~graphics-drivers/+archive/ubuntu/ppa. However, I noticed on a couple of the other similar bugs that have been reported, this repo can also provide packages that prevent the upgrade from working.

So, I'm trying to purge that repo and downgrade the packages, but when I run `sudo add-apt-repository ppa:graphics-drivers/ppa` I get an error that it cannot find the package list for this repo, and as such it refuses to remove it and make the necessary changes. I tried adding the repo again, and then running the same command again to purge it, but same issue.

I just want to get this sorted out. What do I need to do to get this to work properly, short of having to wipe my entire machine, do a fresh install, and spend a week or more restoring my settings and data from backups?