I have a headless Mac mini that currently runs macOS Sierra. I typically control this machine using Screen Sharing, which works fine even when rebooting a machine.

I'd like to upgrade the machine to macOS High Sierra, but am not sure if a complete OS install will work using Screen Sharing. Perhaps it will disable Screen Sharing for security reasons upon install, perhaps there are dialog boxes which have to be answered before Screen Sharing is enabled, etc.

Does anyone have experience doing this?

  • Don’t have experience. One idea is to bring it to the Apple store and plug into their monitor and usb keyboard and install there. Worst case have a genius help you. – JBallin Dec 26 '17 at 7:25
  • No such stores here. I’ve not gone ahead on the install, just wondering before I do. – Rob de Jonge Dec 26 '17 at 7:26
  • Ah but unfortunately there are no apple stores in Bangkok, although it looks like one will arrive soon. Regardless maybe you have a friend or an Internet cafe or tech store that can accomplish the same task. – JBallin Dec 26 '17 at 7:27

I've tested this by screen sharing a VM and it seems to work great!

Using macOS screen sharing app, connect as an administrator and be the only user logged in to the machine at the moment. If, on connecting, you get a message that another user is logged in and whether you want to share session or create a new session, cancel and log in as the correct user. The update will proceed correctly regardless of whether you do this, however you won't be able to see the progress of the update, as other sessions are disconnected immediately.

I'm not aware of any macOS update which has ever required input outside a user account. The setup assistant (‘Sign in to iCloud’, etc) happens after you log in to your user account again, which is usual screen sharing.

Upon starting the update, the user is logged out but the progress bar is still a standard macOS application. Screen sharing continues to work fine at this point.

Once the ‘progress bar’ stage of the installation is complete, the machine reboots, and screen sharing is disconnected. macOS screen sharing app shows ‘reconnecting’ and eventually the connection is resumed. If your Mac takes a while to reboot, screen sharing may time out, so wait a while and manually reconnect.

If you have Little Snitch installed, it should be fine, but might also be worth choosing ‘Silent Mode — Allow Connections’ just in case for the duration of the update.


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