This seemed to be meaningful, but was ultimately a wild goose chase. I was unable to boot into Single User Mode ( Cmd+S+Pwr), but it and Verbose Mode ( Cmd+V+Pwr) did show that the boot process was hanging and the last message it displayed was: pci pause: SDXC I reset the SMC ( Shft+Ctrl+Opt+Pwr while off, then Pwr), I reset the PRAM ( Cmd+Opt+P+R+Pwr while booting, then hold until the chime sounds again), I tried to boot into Safe Mode ( Shft+Pwr).

Thus when I was notified that it was available, I dutifully upgraded… and then my MacBook Pro Retina wouldn’t reboot. After Update, OS X Won’t RebootĪfter upgrading to OS X El Capitan (10.11) when it was released, I had been generally pleased with the new version but there were a few quirks – like random beach ball pauses – that made me think the 10.11.1 update would address some of them. It seems to have left behind a kext named .kext and once I deleted it, things work again. Before I knew this I installed Malwarebytes to check for spyware/adware causing the CPU usage, then uninstalled it after installing the OS X beta. I am using the Beta version because 10.13.2 had very high CPU usage by the WindowServer process that was fixed in 10.13.3. Update – I updated to 10.13.3 High Sierra Beta 5 and once again was unable to boot.

Removed everything older than 2016 after running ls -lat. This time I had to remove kexts from /System/Library/Extensions. Update – I updated to 10.12.6 and once again was unable to boot. Update – This has been an issue for myself and others running OS X Sierra as well. Update – It happened again when I updated to 10.11.4! Even fewer clues this time, additional details and an updated script to remove non-default kext files at the very bottom.

Otherwise feel free to read the saga below!

If your OS X El Capitan/Sierra/High Sierra update won’t reboot you can skip to the fix or check here for the (mostly) automated fix script.

Os x el capitan vs sierra