Not yet ready for macOS Big Sur in your environment, but you’ve trained your folks to look at the Software Update preference pane to see if there’s available updates? One of the ways Apple is advertising the macOS Big Sur upgrade is via the Software Update preference pane:

You can block it from appearing using the softwareupdate –ignore command, but for macOS Catalina, Mojave and High Sierra, that command now requires one of the following enrollments as a pre-requisite:

• Apple Business Manager enrollment
• Apple School Manager enrollment
• Enrollment in a user-approved MDM

For more information on this, please reference the following KBase article: https://support.apple.com/HT210642 (search for the following: Major new releases of macOS can be hidden when using the softwareupdate(8) command).

For more details, please see below the jump.

Once that pre-requisite condition has been satisfied, run the following command with root privileges:

softwareupdate --ignore "macOS Big Sur"

You should see text appear which looks like this:

Ignored updates:
(
"macOS Big Sur"
)

The advertisement banner should now be removed from the Software Update preference pane.

Note: If the pre-requisite condition has not been fulfilled, running the softwareupdate –ignore command will have no effect.