Thanks for sharing your workaround. I would however like to find the root cause of the issue so this can be avoided in the future.This didnt help.
What I have done:
1. Fixed a line in code (removed pvescheduller restart), thanks to advice from previous page
2. Fix corosync conf desynchronization (by coping new version of corosync.conf to buggy node)
3. Reconfigure by dpkg
4. Restart daemons or reboot
Regarding (1.): Yes, this will work as by removing the restart of pvescheduler, you work around the hanging part of the postinstall script, therefore my question, where you able to successfully restart the pvescheduler.service afterwards?
Regarding (2.): This might be the interesting part, as you stated that the cluster was quorate before you started the upgrade process. Could you share the systemd journal during the upgrade, maybe there is something to learn from there?
journalctl --since <DATETIME> --until <DATETIME> > journal.txt
dumps the logs into a file.Regarding (3.): So once you had quorum again, for you it seems everything works again as expected. For @slekkus this seems to not be the case.