Yesterday afternoon it took several hours before the “upgrade” of my mid-2015 iMac (with its spinning platter system disk) reached the “Setting Up Your Mac” screen. Then I waited. And waited. After 2 hours, I was still stuck on that screen, so I finally gave up, crashed out of the install and rebooted. It booted to a progress gauge that was about 85% filled. Then, after a few minutes, I was logging in to Catalina, having never seen the “Setting Up Your Mac” screen again. Last evening I learned my brother had exactly the same stuck on the Setting Up screen problem, and he, too, had to do the same thing I did. I wonder if Apple ever tests their installers on actual user systems. Status: pissed off and stressed out. Thanks, Apple!