Catalina destroyed my MBPr mid 2012 (I keep waiting for a compelling MBP upgrade, and each year the options are worse) Took me days to fix. I thought it was just a security patch installing. It rebooted, got to 100% progress bar then powered down. Did that over and over. Tried reinstalling from r partition. no joy. Over and over. Safe mode... no worky. Single use mode only. Copied all data off onto external drive using that. After days, I had to comletely blow away the entire internal drive, hidden artitions and all, and reinstall from Mojave on external drive. Reinstalled everything (latest versions only and coied back data, including prefs and app support. Pretty much everything back to working order. Except my keyboard is now flaky, only for keys on the right. Catalina ruined my boot partition, rescue partition, NVRam, etc. No idea what it did. Maybe it hit something installed and barfed but wow, it really made a mess of things. Under Tim, they lost the HW "wars". Except the iMac Pro, you can get better non-Apple HW for every form factor. And MacOS is going backwards faster than everyone else can move forwards. The last laptop I would consider buying was the 2015. I'm a programmer. The keyboard matters. A lot.