New kernel extensions
After upgrading to High Sierra, you’ll need to grant specific approval for new thirdparty extensions you install. Examples are Logitech Options and Intego VirusBarrier. You’ll see an alert saying “System Extension Blocked” that prompts you to go to System Preferences > Security & Privacy.
There, a note will say “System software from developer [Name] was blocked from loading.” Click Allow only when you know that an action on your part has caused this to be listed. All that developer’s extensions within the same app can then run. Extensions installed before you upgraded don’t require reapproval.