The path/ System/Installation/Packages/OSinstall.mpkg appears to be missing or damaged. Quit the installer to restart your computer and try again

I’m having the same problem. I was trying to update two apps before updating new OS. App updates failed so I tried installing new OS. Get the message mentioned earlier. Every time I restart I have to enter my MacBook Pro password. It then goes to the mentioned message/screen. I have a MacBook Pro model A1286. Not sure if the year. It is an earlier keel.

I'm getting the same message...I just got this Mac brand new this past August...