MacBook Pro 2018 Random Restart > Previous shutdown cause: -20

I used to get shutdown cause -20. Then I uninstalled McAfee VirusScan. I still don't know what cause -20 refers to but it hasn't happened since I uninstalled McAfee VirusScan. If you have any software that installs a kernel extension as many virus scanners do, try uninstalling that software or booting in safe mode (https://support.apple.com/en-us/HT201262) and see if the problem goes away.

I to experience the same random restart problem. I agree is seems like some app requested a system restart with no error associated with it. It seemed to be only associated with my account, the guest account did not exhibit the same problem but deleting my old account and starting a new one did not fix it. The only thing that worked for me was to erase the disk and reinstall the OS, like the previous person.

BTW, I installed iStat Menu after I started experiencing the problem so I don't think it was that app.

Before I found this post, a work around for this that I used when I had to leave the computer working on something unattended was to open an editor and make a change to a file but don't save it. The OS will stop the restart until the editor can be shut down. I used emacs but I'm sure any non-cloud based editing SW would work.