OS X Security Update hangs during restart I am trying to install Security Update 2019-002 for OS X Sierra (10.12.6). Everything seems to work until I do the required restart. That starts out okay, but eventually, it says "5 minutes remaining" and just hangs there for hours, at which point I force restart, and the computer works fine (but the update has not been applied).

I've retried this a few times, but it always gets stuck in this same spot. I have tried installing the update both with the app store and with the DMG download available from the Apple support website. There are no error messages present.

Is there any way to diagnose and or fix this (short of a clean install)?
Booting into Safe Boot and then installing the .dmg image of the update worked for me. If I tried to install it via the App Store my computer would get stuck even before displaying an estimated time remaining.