About 5 days ago, I finally updated from Mojave to Cat.(wouldn't have if I had read your posts). While trying to figure out how to boot up disk on my ext 3gb HD (not ssd), I started getting panic attacks. I was also using Superduper to do clone to HD. ,, So, after seeing posts of Panics,, I tried a couple of things from Mcrumors posts, and a few others. Went to settings, Energy Saver to check things out.. I didn't have Power Nap enabled to begin with, so one of recommendations was to disable it,, think I changed turn monitor off to 15 minutes (might have been an hour before). Don't ask me why I put it to 15 min not Never, that might have been more logical seeing as Secondary monitors seem to be one of the causes of Panics. Also, I do have an Glyph Thunderbolt dock, where I have secondary monitor attached to, as well had one ssd and one normal HD where I was doing my Superduper transfer of files for Clone..
I ended up unmounting my TB dock, and overnight left it. I expected, that after iMac being unattended overnighthat for sure I would find my iMac restarted as a result of PA, but No,, it had not suffered overnight. I replugged my TB dock, with ext monitor.and t, and both iMac screen and Secondary, (and even LG tv) which I have hooked up as a 3rd Monitor. woke up nicely (with less than ¼ sec wake up black screen).
Since then, I have completed doing Superduper clone to T5 samsung (had to proper setting for GUID for disk to get recognized). I have not had One panic attack (where is that wood I can knock on). If you have questions for me, let me know,, I can send you screenshots of settings if you like.
I had seen recommendation to go to Overwrite current Catalina using disk Utility,,which worked for someone else,, but never actually got to try it out. I would have been scared that it wouldn't overwrite, and done a clean install. Wasn't ready for that. I have 2019 iMac top specs. with 2 tb Apple SSD. Seems like a lot of you are talking about MBP etc though.
