Remember the "old days", when you called tech support and the dweeb on the other end wouldn't talk to you until you convinced him you turned off your computer, unplugged it, waited 30 seconds, plugged it back in, booted it up and the problem was still there? Oh, wait, that was just this morning!
If the difference between a restart and a power off/on somehow fixes and update problem - then Apple has WAY BIGGER PROBLEMS, than an update problem.
Just for grins, I ran the disk permission - found nothing that should cause this problem. I did RESTART IT, then downloaded and ran manually the CRAW update - and Hey, it no longer hangs on the CRAW update. Do you know what it DOES do? It now wants to reinstall iTUNES 12.2.1 EVERY TIME I open App Store! I let it install it several times - just to see what would happen. It takes just as long each time installing a fresh copy.
So, clearly there is some bug somewhere. I just don't think its in the boot sequence.
I took the next most suggested road for apple bugs and deleted the preferences files update. I then ran AppStore - and Voila! No repeated updates!
me