How to I permanently cure this dialogue? I’m willing to reformat the internal drive again to a blank disk.
iMac Late 2012
MacOS Catalina 10.15 - on internal spinning drive (not used, formatted as bootable today!)
MacOS Catalina 10.15.1 - on main/bootable external USB3 SSD
This morning I installed Catalina on what was the clean/reformatted non-bootable internal drive.
Created an administrator account on the spinner, then rebooted to the external SSD (my main drive).