For many years I have managed Fast User Switching (FUS) on macOS in the maner documented by Apple; with the MultipleSessionEnabled key in the .GlobalPreferences payload. Unfortunately as of Big Sur the documentation is no longer complete.
I didn’t notice until last week but Nathaniel Strauss reported this problem over a year ago in his article “Managing Fast User Switching Broken in Big Sur.” He also recently confirmed that he has had no luck in getting Apple to restore the functionality via that key.
However thanks to a push in the right direction from colleagues on the MacAdmins Slack, I now have control of FUS reliably working via configuration profile or defaults commands. Read on for the details…