I have a 2008 Mac Pro (3,1). Dual 2.8Ghz quadcores, 64GB RAM, and a 2 TB internal SSD. I was running El Capitan and opted to put in @dosdude1 's High Sierra patch in order to be able to run some newer software I couldn’t run on El Capitan. Following his website's instructions, I ended up installing from a 32GB USB thumb drive. I was surprised that, start to finish, it took literally 34 hours to install. I chalked it up to USB 2.0 on a 10-year-old machine being awfully slow by any modern standard, but I’m not so sure that’s the problem anymore. I then ran his post install tool with the default options for a 3,1 Mac Pro, and rebooted into the SSD. It came up quickly with the password prompt (I run FileVault, so the SSD is encrypted). And then the progress bar started moving to load the rest of the OS. It hangs perpetually around 95%. I let it run overnight and then some, and it never got any further. It’s an SSD, so I can’t listen for any hard drive movements or other observable activity in the background. Rebooted into the boot USB, ran the post installer again, and this time opted for the Force Rebuild option for the caches. Rebooted back into the SSS. Same problem. I turned off the machine and let it sit for a while and went back to my MacBook Pro while I thought through what’s going on. Just for kicks, I decided to try building a new boot drive w/ High Sierra and the patch. This time I used a FireWire 800 external 1TB hard drive. Re-ran post install from that drive e and the forced cache rebuild. Same exact problem. When I did the force rebuild, it told me there’s a command I should run from Terminal after booting into HighSierra. I haven’t even been able to get that far to run it. Is there any point in running that command from Terminal from the installer boot drive? Might any of you have any idea what other problems are taking place?