Similar situation, different error. Did upgrade to 28 with the python exclusions:
[user@fedora-28 ~]$ sudo dnf --releasever=28 --setopt=cachedir=/mnt/removable --best --allowerasing distro-sync -x python2-xcffib -x qubes-gui-vm -x qubes-gui-agent Then: [user@fedora-28 ~]$ sudo dnf swap python-xcffib python2-xcffib Error: Failed to synchronize cache for repo 'updates' -- You received this message because you are subscribed to the Google Groups "qubes-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to qubes-users+unsubscr...@googlegroups.com. To post to this group, send email to qubes-users@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/qubes-users/1b8d35c9-5f62-405d-b77c-8f4a406c92a1%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
