How can I find out what the problem is with my failing CiviCRM installation in WordPress?
I think you need to add an extra step or two. See https://docs.civicrm.org/sysadmin/en/latest/misc/switch-servers/ for more details

Deactivate old version and backup a copy of the CiviCRM database from the old install

Do your install in the new location and then activate with a new (empty database)

Rename the old Civi database as temp, restore the old database, rename the restored database as the new Civi database (and set up user as it was before).

Rename temp back to old Civi Database and reactivate old install so that it continues to work.

If you have changed to a subdomain you may need to edit some other resource settings.


I think the reason you need to take this approach is because of the settings stored in the database. I did quite a lot of trial and error to work it out in my environment (some odd things happened with my hosted server and subdomains.