I tried the beta and here are my observations:
- vmail user homedir does not exist anymore (used to be /home/vmail but now /var/vmail), preventing fetchmail to start. A possible workaround is to create /var/vmail with vmail:mail ownership
- php7.3-fpm.service failed to restart, but restarting it manually after the upgrade works fine
- postfix regen-conf failing with the error
Warning: postmap: fatal: open database /etc/postfix/sasl_passwd.db: Permission denied. It looks like the issue stems from /etc/postfix not being writeable by the postfix user, preventing postmap to create the /etc/postfix/sasl_passwd.db. A workaround is to generate is manually at least once:
chown postfix:root /etc/postfix
postmap /etc/postfix/sasl_passwd
chown root:root /etc/postfix
I also saw the OOM-killer being triggered reliably during the upgrade on a 512MB VM, I had to increase memory to 1GB to avoid that - so you might want to stop as much services as you can prior to upgrade if you have a small system.
Hope this helps, and thanks for the hard work!