Must shutdown to update? Hadn't seen that before

[Paco II]

For years I was running a headless Mac mini 2012. I do my updates via screen sharing and using Terminal (softwareupdate followed by authenticated restarts). Always worked fine. I recently acquired a 2018 Mac mini to replace the 2012. I followed my usual steps via Terminal to installed 10.15.4. But this time I got a strange message. After Terminal indicated that the update was installed, there was a message saying that I must shutdown to finish the update, that the update will automatically restart the mac, but that I must do a shutdown. It said a restart would not complete the install. I have never seen this before. Sure enough, I did a shutdown, and the computer restarted itself and completed the update. Is this something unique to Catalina, unique to 10.15.4, unique to the Mac mini 2018, or something else?

 

[OldGreyGuy]

Happened to me on the two 10.15.4 supplemental updates I have done

 

[Paco II]

Weird! But glad it wasn't just me ? I don't really think of a shutdown as being so different from a restart, but this is a reminder that it clearly is.

 

[oatman13]

This is normal if you have a Mac with a T2 chip.

 

[Paco II]

Does this mean I'll never be able to do a remote update, since it requires an authenticated restart to be able to log in again remotely (filevault is enabled)?

This is normal if you have a Mac with a T2 chip.

 

[oatman13]

Does this mean I'll never be able to do a remote update, since it requires an authenticated restart to be able to log in again remotely (filevault is enabled)?

The software update mechanism will handle the authenticated restart.
Your machine should end up with the disk unlocked, sitting at login window when the update process has finished.
(You should be able to SSH in, etc)

 

[Paco II]

Thanks. Next update I'll give it a try.

Still, an odd message. Any idea why a shutdown is required?

The software update mechanism will handle the authenticated restart.
Your machine should end up with the disk unlocked, sitting at login window when the update process has finished.
(You should be able to SSH in, etc)

 

[oatman13]

Thanks. Next update I'll give it a try.

Still, an odd message. Any idea why a shutdown is required?

I don't believe that answer is known outside of Apple.
All that's known is that it's required for T2 Macs. If you restart on those devices the T2 firmware won't apply itself and you'll be sent to the Recovery OS to redownload/install the T2 firmware before you'll be allowed to use your Mac.

So in your case, if you want to end up at login window where you can SSH back into your Mac, definitely do what is asked by the Software Update command line utility.
You can also pass --restart and it states that it will handle it for you.
[automerge]1586744844[/automerge]
The man page states:

-R | --restart
Automatically restart (or shut down) if required to complete installation. If the user invoking this tool is logged in then macOS will attempt to quit all applications, logout, and restart. If the user is not logged in, macOS will trigger a forced reboot if necessary. If you wish to always perform a forced reboot, pass -f (--force).