I did upgrade my Virtualmin to 7.7
I had to run sh virtualmin-install.sh --setup force-latest to get it.
It didn’t make a difference to the usermin/webin updates. Still the same key error.
I am wondering if I need to run setup-repos.sh that iliajie indicated in that post. This stuff makes my brain hurt. I guess I should have switched to Ubuntu a few months ago. My Ubuntu server is updating without an issue.