Apple Silicon M1 Macs and MacBooks are falling victim to a bug that sees the screensaver forcibly take over the screen without warning, leaving users unable to continue working — though there are several short-term fixes available.
Per MacRumors, the issue appears specific to Mac and MacBook hardware with the Apple M1 chip, and is caused by the new Fast User Switching feature in macOS Big Sur. While this is supposed to let users switch accounts without needing to fully log out, the bug it’s apparently causing makes it difficult to log in or out at all, as the screensaver leaves the desktop space unusable despite the mouse cursor remaining visible.
M1 Mac and MacBook owners report the screensaver popping up randomly, and up to several times a day. Once it appears, it’s effectively stuck there, with simple cursor or key inputs unable to shift the image as they would with a non-bugged screensaver.
One user on the Apple community forums said that disabling the screensaver prevented the bug from occurring again, but many more claim this has no effect.
Luckily there are more reliable ways of wrestling control back from the screensaver. One of the most consistently reported solutions for MacBook users is to close and open the lid, which gets you back to the login page; the same result can be attained by light-pressing the Power/Touch ID button or pressing the Alt, Command and Q keys together.
Affected users can alternatively disable the Fast User Switching feature entirely. Obviously, none of these solutions are truly ideal: you either have to interrupt yourself to return to the login page, or disable a new and potentially useful software feature. Here’s hoping Apple is aware of the problem and is working on a more permanent fix.