This happens to me sometimes and I just leave it to download, mine usually finishes in a few seconds, but what I recommend is leaving your pc on over night with the update running and see what happens in the morning.
Also try see if you drives are not full because some of my games would crash due to all of my drives being, so I wiped my pc cause I never knew what took up all the space on my drives, and now pretty much all my games never crash.

This happens to me sometimes and I just leave it to download, mine usually finishes in a few seconds, but what I recommend is leaving your pc on over night with the update running and see what happens in the morning. Also try see if you drives are not full because some of my games would crash due to all of my drives being, so I wiped my pc cause I never knew what took up all the space on my drives, and now pretty much all my games never crash.