I solved the above issue. There was some issue on the install of php8.0, so I reinstalled it and then had to a2enmod php8.0 and then restart the Apache server.
I was then able to apply Patch 3 to my default site.
However, when I use admin.php to try to apply the patch to another site in our multi-site module, I see the link for Patch Database for the other site: “http://IP address/openemr/sql_patch.php?site=XXXX”.
When I click on this, it tries to take me to this path: “http://IP address/login/login.php?site=XXXX”.
This is the wrong path, as that file is at “http://IP address/openemr/interface/login/login.php?site=XXXX”.
So the root appears to be off. The patch doesn’t go through for the other site.