Any major upgrade to the macOS comes with a few issues. Most of the time those issues are fixed in the first and second update to the new OS. macOS High Sierra is no exception to this behavior, people are finding a few issues with the new OS. One of those is their Macs are being logged out without their permission.
Unwanted Log Outs
If you have installed macOS High Sierra and your Mac occasionally logs out on it’s own then read on. There is a setting on your Mac that is turned on and needs to be turned off.
Go into the Security & Privacy Preference Pane. Make sure the “General” tab is selected, then click on the “Advanced” button bottom-right corner of the window:
When you click on “Advanced” a drop down menu appears with two settings:
For what ever reason, sometimes a High Sierra install comes with that “Log out after” setting checked. The default is 60 minutes. All you have to do to stop these logouts is uncheck that box:
Now your Mac should be free of unexpected logouts.
Yes, there are a few minor problems with macOS High Sierra. However, I do not regret installing it, I really like it. I am sure any current problems will be fixed in future updates.