Kernal changes in macOS High Sierra
1 Warning dialogue
Watch out for a dialogue like the one above when installing software in High Sierra. If you happen to dismiss this dialogue too keenly, chances are you’ll notice quickly as your software, or some of its features, is unlikely to work.
2 Security & Privacy
Go to > System Preferences > Security & Privacy > General. Toward the bottom of the window you should see a warning and an Allow button. Only click the button if the prompt was shown due to deliberate action on your part.
3 Allow permission
If there are several extensions awaiting authorisation, you’ll see a list of them – this is likely if you’ve restored your Mac from a backup. Check the boxes for items you recognise, then click OK; you may be asked to restart your Mac.