Hi Kyle,

Reading this was eye-opening:

My recommendation is to just upgrade Joomla 3 to Joomla 4 then move the necessary database tables over to your new install and you should have a completely functional migration of user data on a clean Joomla. The tables you'd need to migrate are as follows.

_users
_usergroups
_user_usergroup_map
_viewaccesslevels

All tables beginning with any of the following.

_comprofiler
_groupjive
_cbsubs

I'm planning start from scratch to completely rebuild a 15-year-old site that has a template with no Joomla 4 upgrade path, but copy across the data from big extensions like CB.  I was thinking the major extension databases would likely change from Joomla 3 to Joomla 4, so that I'd have to uninstall as much as possible from the Joomla 3 site, take the old site with the extensions I need through Joomla's upgrade process, and then copy the resulting relevant tables to a clean Joomla 4 installation.  But are you saying the CB table structure is the same between Joomla 3 and Joomla 4?  That'd be a lot easier.  Could I just start with a clean Joomla 4 site, migrate the tables you list directly from the Joomla 3 site to the fresh site, and then install CB and all plugins on the fresh site?  (Plus, of course, copying the needed profile image files, attachments, etc. in the same locations.) 

Is that what you were saying, or do I need to go through the Joomla Upgrade process just to get the proper table structure first?

Finally, regardless whether I have to move Joomla 4 tables or Joomla 3 tables to a fresh Joomla 4 site, is the correct order to copy the tables first and then install CB afterward?

Thanks for the help!