Hi Paul,
Looking through the tar file you sent me I see a few things going on here:
It looks like upon the upgrade the Pulp3 migration tool was upset about the debian plugin and some permissions on the pulp directory:
PermissionError: [Errno 13] Permission denied: '/var/lib/pulp/assets/admin/css/autocomplete.css'
Is that set to pulp:pulp also try a # restorecon -Rv on it to see if something got messed up with SELinux
Are you using Debian files with your Katello instance?
I see in /etc/foreman-installer/scenarios.d/katello-answers.yml that it is enabled
enable_deb: true
I do see Pulp3 on as well in the same file:
pulpcore_enabled: true
If you are not we can verify there is not any Debian repos/files being used by doing the following:
# foreman-rake console
Katello::Deb.count
Katello::Repository.where(:root => Katello::RootRepository.where(:content_type => "deb")).count
If both of these are 0 then you can safely disable deb content in katello before migration by running foreman-installer --katello-enable-deb=false
Then we can try the upgrade again.
I see there was an issue filed for this as well: