Screensaver comes on randomly and prevents use in Big Sur and M1

Lots of ideas about what might cause this issue have been floated (and rejected) here, and the idea about Hot Corners was an early guess, and quickly rejected.

The ongoing issue seems to be related to Fast User Switching -- where you log in a second user on top of the first User without logging the first User out. Even if the backgrounded user does not have settings for screensaver, it seems to come on anyway.

Grant, your hypothesis doesn‘t seem to hold. I have two accounts on my M1 macMini, but my wife was not logged in, when „ScreenGate“😀 happened to me.

I use two workarounds

1) Right clicking in the screen saver makes the unlock screen appear where you can enter your password. Don‘t enter the password but click on „change user“ at the bottom of the screen. All accounts on your computer appear. Chose your own one, login and you‘re in.

2) I set my macMini to not go to sleep and my monitor to turn off after 5 minutes. When „ScreenGate“ happens, wait until screen turns off, hit a key on the keyboard and you‘re back in again.

This is happening to me too. I’ve been able to get around it twice by clicking switch user and then clicking my profile (never actually switching the user) and then typing my password. If I just log back in with my password without clicking switch user first, then I get the screensaver when I log in. Strange!

I closed the lid for a second it worked, I found this one more convenient than setting up hot corners to being it back. The point is why do we need to do it after we disabled screen saver and it still shows up?

For anyone having this problem, you don't have to restart the mac. You can press the power button and switch user. When you switch back to your profile, the screensaver will be gone.

I, too, am having this problem.

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Engineering action is based ONLY on Bug Reports filed through Apple Support, and items returned from service visits. If you have an ongoing problem and cannot get by with the work-arounds already posted here, be sure to contact support and have them file a Bug Report. The link to get started is at the top of every forum web page.

Trying the "sudo defaults write /Library/Preferences/com.apple.screensaver loginWindowIdleTime 0" (run in a terminal ) solution right now..

Will keep you posted of the results... seems to work according to mac rumors community.

When it happens try closing the lid for a minute. Works for me

Nope it didn’t work for me. Closing Laptop screen for about a sec or two and re-opening it is the least painful thing to do to recover from it.

I just close the MB and open it again, seems the fasted way, since user switching won't work most of the time

Have you applied the update to 11.2. That presumably fixed the problem.

A “not really a fix-fix” is to simply close the lid and reopen

It’s been fixed. Make sure your OS is up to date.

I‘m on 11.2.2. Please update.