Auto shutdown at night after High sierra upgrade
Installing "command line tools" solved this issue. However, I have no clue how they are related.
To install command line tools run following command in terminal.
xcode-select --install
I have had the same issue each day since installing High Sierra. However, in my case, the computer doesn't shut down, but rather goes into deep sleep. I called AppleCare and they acknowledged the issue and said they are working on it.