Upgrade to version 26 process froze

[wagnered]

I waited awhile for it to finish upgrading the Thunderbird package then I walked away for supper returning about 30 minutes later, it was still on that step.

Because I couldn't ctrl-C out of it, I closed the terminal. then rebooted.

Now when I run the dnf command it reports that "Failed loading plugin: system_upgrade" ,
It doesn't exist in /usr/lib/python3.5 or /usr/lib/python3.6 but does in /usr/lib/python2.7.
I tried reinstalling it again but it indicated that "python3-dnf-plugins-extras-system-upgrade-0.10.0-1.fc26.noarch is already installed" and when I tried reinstalling the package, it indicated it isn't available.

Is there a way to repair, downgrade, clean the dnf database to return it to version 25? Dnf check reports a large number of conflicting files between fc25 and fc26.

Thanks
Ernie Wagner