Update manager can't calculate solution due to no candidate for ubuntu-minimal

[Eloque]

Upgrade from 16.04 to 18.04.
Tried to apply fix for unescaped &
Dist-upgrade log shows long list of 'broken' packages when attempting to do-dist-upgrade
apt update and apt upgrade work seemingly perfectly.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.25
ProcVersionSignature: Ubuntu 4.4.0-131.157-generic 4.4.134
Uname: Linux 4.4.0-131-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CrashDB: ubuntu
Date: Sat Aug 11 18:33:46 2018
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to xenial on 2018-08-11 (0 days ago)
mtime.conffile..etc.update-manager.release-upgrades: 2018-08-11T17:00:09.348260

[Brian Murray (brian-murray)]

You appear to have packages installed from the -updates pocket of the Ubuntu archive, but you don't have it enabled in your /etc/apt/sources.list file. Please add it to your sources.list file and then run 'apt-get update' and then try the upgrade again. Thanks and good luck.

[Launchpad Janitor (janitor)]

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