ALKaleideum
Did you ever develop a process for this? I'm in a similar situation, going from CA1.8 to 2.0 and Ubuntu 20.04 to 24.04.
But it's a catch-22. I can't figure out which to upgrade first. CA 2.0 needs PHP8, which isn't available in 20.04, so I can't start there. And 22.04/24.04 doesn't include PHP7, which is needed for CA 1.8.
The only idea I have is to back everything up (as per @jeffschneider 's URL), upgrade Ubuntu all the way to 24.04, then install all the CA 2.0 requirements, then install CA 2.0 over 1.8 and fire Apache2 back up (and keep my fingers crossed).
Alternately, back everything up, start with a clean 24.04 server, install CA 2.0, then restore everything from backup. That's clean, but I have to requisition a new server, requisition a machine name change, etc, and that'll all take longer and have it's own problems.
Any advice or experience with this?