The path /System/Installation/Packages/OSInstall.mpkg appears to be missing or damaged - OSX 10.13.1 - High Sierra This is not a duplicate of this question. The situation is a bit different. In my case, I have already installed High Sierra on a MacBook Pro 15inch 2017. I encountered this issue when updating the Security Update 2017-001. It got stuck in a boot loop where upon entering my password, it would send me to install High Sierra. (I've installed it over a month ago). Then it would show this error.
My solution which has not been mentioned in the locked thread, is to hold the option key upon startup to use the Startup Manager to select out of the OSInstall route. Hope this helps anyone else running into this issue, as I've spend too many hours trying to fix this.