I'm using Ubuntu 18.04.2 LTS.

My PC (not a laptop) shutdowns randomly after a few days it was on. The shutdowns occur while I didn't use the computer for few hours, after few days it was on.

I dug into the logs file and didn't find anything unusual (I'm newbie though).

I checked for future scheduled shutdowns, and got that:

I'm adding here the screenshot of the logs before the shutdown,maybe someone here will figure out what is going on and how I can prevent the shutdowns, thanks.