This! Microsoft should have issued the warning, strongly.
I ran into this problem on 3 different laptops all using different Virus/Malware protection. The best option if you get hit is to chose to roll back the system to the state before the update. (don't bother with system restore it doesn't work for this large of an update), then turn off the Virus/Malware protection, update, check for more updates, update whatever it offers, reboot then reactivate your virus/malware protection.