Could not calculate the upgrade while upgrading from 17.10 to 18.04

[Parth Sahni]

An unresolvable problem occurred while calculating the upgrade.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: ubuntu-release-upgrader-core 1:17.10.11
ProcVersionSignature: Ubuntu 4.13.0-40.45-generic 4.13.16
Uname: Linux 4.13.0-40-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.7-0ubuntu3.8
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 30 14:43:54 2018
InstallationDate: Installed on 2018-01-09 (110 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Release amd64 (20171018)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to artful on 2018-04-30 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

This likely has something to do with the following two PPAs you have enabled and installed packages from.

./etc/apt/sources.list.d/ondrej-ubuntu-nginx-artul.list
./etc/apt/sources.list.d/ondrej-ubuntu-php-artful.list

Please remove those PPAs using the tool ppa-purge and try the upgrade again. Thanks!

[Launchpad Janitor (janitor)]

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