Failed upgrade to Zesty - Could not calculate the upgrade

Trying to upgrade from 17.04 to 17.10, I am getting the message "Could not calculate the upgrade".

I have seen the bug https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1069160 which seems similar, but refers to earlier releases (and is marked as invalid), so I am reporting a fresh bug. Bug 1069160 was resolved by a couple of people by removing xserver-xorg-video-nouveau,
which I also have installed, but attempting to remove this will also remove xserver-xorg-video-all, and then makes a whole list of xserver-xorg-packages "no longer required", including the one for my graphics card - so I am reluctant to remove this package.

I cannot work out whether I have unsupported packages which are preventing calculation of the upgrade (I had a look through the apt.log but couldn't work out where the error was).

Thanks in advance for your help. I've attached the apt.log file, and will attach the main.log file in a comment.

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: ubuntu-release-upgrader-core 1:17.04.10
ProcVersionSignature: Ubuntu 4.10.0-38.42-generic 4.10.17
Uname: Linux 4.10.0-38-generic x86_64
ApportVersion: 2.20.4-0ubuntu4.5
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity:Unity7
Date: Sun Oct 22 17:25:42 2017
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to zesty on 2017-10-22 (0 days ago)
VarLogDistupgradeTermlog: