Grey screen on system wake up

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Level 1

15 points

Grey screen on system wake up

My iMac is set by schedule to sleep overnight, 10pm-8am. The last few mornings when I try to unlock the system (typically around 9:30am), the screen background is entirely gray. On one occasion, the bluetooth mouse was frozen. On the other occasions, when I was able to unlock the system using my password, there are error alerts saying "Unapproved caller. Security agent may only be invoked by Apple software". Also "iCloud Drive may not work properly. Please check the iCloud Preference Pane. Couldn't communicate with a helper application".

Also Finder appears to have crashed and not restarted properly – there is no menu bar and apps (e.g. System Preferences) will not start. The Dock crashes and restarts as I try different ways to get the system working.

Using the power switch, I force the system to shut down and on restart all comes up apparently OK, except that Time Machine does not run on its normal period basis (I have two TM drives) until I manually start a backup, which appears to clear the "blockage".

I have started the system in recovery mode and run Disk Utility on Macintosh HD. It said all was fine. The next morning the problem recurred, so I went into recovery mode again and reinstalled the system software (Catalina, 10.15.6). The problem happened again the next morning.

I'm at a loss! Can anyone suggest another route for diagnostics or even repair?

Many thanks.

iMac Line (2012 and Later)

Posted on Aug 11, 2020 11:17 AM

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Answer 1

dpol Author

Level 1

15 points

Aug 13, 2020 2:17 PM in response to tpaiget

tpaiget, thanks for the response.

The good news is that the problem has not recurred. I spoke to Apple Support, who recommended restarting the machine in Safe mode, which would clear the caches and then starting with opt-cmd-P-R to reset the PRAM and NVRAM. I did as suggested and the first-thing-in-the-morning problem did not recur the following day. However, on a wake from sleep later that day, the system showed a black screen behind the login fields and neither mouse nor keyboard (both bluetooth) would accept input.

The following day Apple released a supplemental update to 10.15.6 (which I was running). Interestingly one of the reasons for the supplemental update was to fix a problem (presumably introduced in 10.15.6) concerning wake from sleep in 2020 iMac 27" with 5K displays. That's just a newer model of what I am using (mine's late 2015).

It seems possible that this bug affected my machine, since the problem only occurred after I'd updated to 10.15.6.

Anyhow, since applying the supplemental update (yesterday), I've had no problem at all, so I'm keeping my fingers crossed.

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Answer 2

tpaiget

Community Specialist

Aug 13, 2020 10:29 AM in response to dpol

Hi dpol,

It sounds like you may be experiencing an issue with your Mac starting up to a blank (grey) screen accompanied by some other indicators of issues by your description of crashing behavior. Congratulations on being so proactive and taking some steps to troublshoot the device on your own.

You may find the following article useful in understanding the troubleshooting steps we have the capacity walk you through: If your Mac starts up with a blank screen.

However, based off your description of the steps you've taken thus far, it sounds like you've been very diligent.

In the event the article offers no resolution, please reach out to Get Support to discuss options for further service or repair.

Have a great day.

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Answer 3

bailier

Community Specialist

Aug 13, 2020 3:21 PM in response to dpol

We look forward to you keeping us updated.

Thank you so much for using Apple Communities.

We appreciate the opportunity to get you back up and running!

Have a great day!

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Grey screen on system wake up

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