Installed:
SPPB 3.8.10
Helix Ulitmate v2.0.13
J4.3.2
Updated a few websites from previous versions without any issues.
Installed extensions/plugins: Only the important ones that are really needed like the ones from Akeeba.
Tested first local on Mamp Pro, then on Litespeed based servers.
PHP version: 8.08
Tip:
Have a subdomain with a testing site with about the same setup/installed plugins/extensions as the main sites you run. Can save you some of headaches.
Just for info..
