MP 6,1 Displays won't wake up after Big Sur update.

[peterlemer]

I might have found a fix to stop my DELL U2913WM monitor being disabled by my iMac.
In System Prefs./Energy Saver - I uncheck 'Put hard discs to sleep when possible'

Try it, let me know

pete

 

[EdwardC]

Same issue here with M1 Mini, If left too sleep overnight the computer will awake as you can here the keyboard tone when pressing the space bar, no signal to the HDMI port from what I can tell. Unplugging and re plugging in does nothing either. Solution......Turn the Mini off at night and restart the next day. Kind of sad but I figured being a new device there would be some sort of issue.

 

[th0masp]

"The computer has to be in sleep mode for a bit (half hour or more) to experience the issue"

Could it be an issue with sleep vs hibernate mode? AFAIK by default after a set period of sleep time the computer transitions from normal sleep into the latter. That might explain why it takes a while/overnight for the issue to show up. From what I remember those default values are quite different for desktop vs laptop devices.

Might be worth playing around with the settings for hibernate via pmset in terminal to see if turning it off entirely or triggering it earlier helps to track down the issue.

 

[peterlemer]

OK. I can report a fix! PREVENT COMPUTER SLEEP WHEN DISPLAY SLEEPS.