Same here, I tried the combo update from the mac app store (I'm on 10.13.1) and the 10.2 installer as well, and it always reboots during the "black update screen" before completing it. Then I find the "Install mac os" boot option but it always freezes during loading. Also strange fact : this partition never went away after I did the original install, It was always there and I thought it must have been normal, but now I'm starting to doubt it...
Ideas anybody ?
Thanks !