I had the same problem with KB4054517, PC got several time stuck at "Getting Windows ready..", I could only hard-shutdown.
First I did was stop Windows Update in services, then I deleted everything in Windows update cache C:\Windows\SoftwareDistribution\Download , restarted PC, and then manually downloaded and installed correct offline version from Microsoft Update Catalog , after succesfull install, restarted again, enabled Windows Update in services, and that solved the problem for me.
Have you tried this troubleshooter. Try running it 2-3 times.
Also check for any damaged system files by opening a cmd window (with admin privileges) and copy-paste this sfc /scannowand press enter.
If you still get error, disable any security software you have on your system (I would recommend temporarily uninstalling all security software) .
I had problems installing this update as well. On the fourth reset of my pc, I had downloaded the stand alone installer and had it on a flash drive. I had my ethernet cable unplugged and skipped the connecting to a network portion of the windows setup process. As soon as windows was ready, I manually installed KB4054517. The update went through. I reconnected the ethernet cable and connected to my fios server and ran windows update to get any other pending updates.