Oh I found this info that I missed, it seems I cannot migrate to almalinux8 before UBB8.
see below I need to upgrade first to UBBThreads ver 8, PHP is ok with 7.2+ , MySQL needs version 8 so UBB8 will be needed first for me.
Upgrading a cpanel server to almalinux8 generally goes smooth. The method we uses to upgrade is as follows:
* set up a new almalinux8 server with cpanel (stable version)
* Match mysql versions, if possible. MySQL 8.0 is the lowest possible version supported on a new almalinux8 install but it is possible to go to mariadb 10.3 too.
* Match PHP as best as possible. PHP 7.2 is the lowest version supported by a new cpanel install. The new set up allows the choice php of 7.2,7.3,7.4, 8.1, 8.2 per domain in multi php.
* Once set up all accounts are copied over from the old server to the new server. Then data is kept in sync using rsync, and a time for a final change over is chosen. A final sync is done, and the ips are moved from the old server to the new server. The downtime is generally in total under 30 minutes.
Some things to keep in mind: Pop before smtp is off by default, but still can be enabled. SSL certificates are free using cpanel's autossl on the centos7/cpanel set up..
