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Fast User Switch Stopped Working  



I use fast user switch A LOT. I set up a separate user account on my mac (iMac 27 in 2017) for each of my clients and I have my own general purpose account that is always logged in. I'm usually logged into 2 accounts at once, sometimes 3. A few days ago I updated from 10.14.5 to 10.14.6 (18G87) and fast user switching no longer works. If I try to log into a second account, the login screen appears, I select the account I want and enter my password. At that point the password box goes away and the white "windmill" starts spinning. So far all seems normal, then one of two things happens. At best, I'm suddenly bounced back to the login screen but without any logged in users at all. At worst the windmill stops spinning and my mac hangs and I need to use the power button to shut down.

I've tried-

  • cleaning things out with Onyx- didn't help
  • disconnecting all peripherals (only ethernet connected, nothing else)- didn't help
  • Booting into safe mode- everything was fine, but only in safe mode. When I rebooted as normal, fast user switching reverted to not working.

From that I figure it has to be something launching at login. I removed all startup items and for those things that don't appear in the startup items (Bartender, 1password mini, etc) I told them not to start at launch in their preferences. That left only Malwarebytes which does not seem to allow you to prevent it from starting. None of that helped. So i removed Malwarebytes from my system. As far as I can see the only sign that I ever had it installed is in the SystemMigration history folder in a QuarantineRoot folder. What is there is a kernel extension but given where it is and that I no longer see the Malwarebytes 'M' in the menu bar, I'm pretty sure that nothing to do with Malwarebytes is running. Searching in Activity Monitor shows nothing related to Malwarebytes either. I still can't use fast user switching.

Anyone have any ideas for something else to try?




See your other post on this same subject.

@datafornothinandbitsforfree thanks I had managed to uninstall malwarebytes but I had forgotten about etrecheck. Will try. BTW that other post was not me. Someone copied my post and resubmitted it as their own. I’ve reported it because I was afraid any useful info would go to the newer post and I wouldn’t be notified.

2 Answers

Ok, problem found. Running EtreCheck was the right suggestion (thanks @datafornothinandbitsforfree). It reminded me of a few things that i had installed that I wasn't thinking about. It turns out that DisplayLink (used to connect additional screens over USB) is the culprit. My extra screen isn't connected at the moment so I forgot about DisplayLink. Updating to the latest version (v5.2 from July) did not help but running the uninstall tool (distributed in the install dmg) did. So if anyone has the same problem, it looks like until DisplayLink is fixed you have to choose between your extra display and fast user switching. I've reported the problem to DisplayLink.