Macbook Pro 16 crashes on sleep when external screen plugged

Yep exactly the same issue here MacBook Pro 16" crashes when sleeping with an external monitor..

panic(cpu 2 caller 0xffffff801669167c): Sleep transition timed out after 180 seconds while calling power state change callbacks. Suspected bundle: com.apple.iokit.IOGraphicsFamily. Thread 0x7cb0.

Same problem here.... MBP 16 (2019) crashes every time I put it to sleep closed with external Dell monitor (s2718d). Doesn't wake up computer or monitor with external keyboard. On opening mac the keyboard will be lit up with display dark and you have to do a hard reboot with the power button. Not the most inspiring way to get to know my new super-duper computer. What are people doing about this again? Is it the OS or the monitor drivers(no mac drivers for my monitor)?

I am having the same problem since the the last update macOS 10.15.5, the only thing I have found to keep it from crashing when connected to an external monitor is to check "keep computer from sleeping when display is off" and leaving the lid of MacBook Pro 16" open, if I close the lid to use it in clamshell mode it crashes when it tries to go to sleep.

I too was extremely frustrated by this (MBP would crash every time it went to sleep while connected to a dock) until I came across another thread here which fixed the issue for me and others. Go into System Preferences -> Notifications -> Do Not Disturb -> Turn on Do Not Disturb and check "When the display is sleeping." This will prevent the OS from showing notifications while your computer is sleeping, which is causing major problems when an external monitor is hooked up. Who wants this feature anyway. It's silly, and it's especially silly that it's causing people's computers to kernel panic.

Hello metmirr,

Welcome to Apple Support Communities. It sounds like you're having trouble with your Mac while it's connected to an external monitor. I'd be happy to share information that may help.

Take a look at the steps here, and give those a try: If your Mac restarted because of a problem.

If those steps do not resolve the issue, please reply with whether or not this occurs when your monitor is disconnected.

Take care.

I'm having same problem since like a month. At the beginning it happened every so often but now it happens every day. MDB 16'' connected to an external monitor vía hub USB-C --> HDMI with no other peripheral than the monitor itself.

U experience the same issue . MBP16 and Dell usb 27 unchaining monitor.

Also happens that in hot weather MacBook start to lag while connected to the monitor. Holds CPU above 70%

Once you disconnect the monitor , computer is back to normal.

I have the same problem... Every day that I close the MBP 16 and use only the external monitor... The same log that you guys.

When the MBP restarts, the fan starting to work harder too..

Apple, what **** are you doing?

I have the same issue with my 16 and external monitor. Each time a few minutes after sleep I get the restart error. For now I stopped using the sleep function, but I am hoping apple will fix this. It used to happen once or twice a day with 10.15.4, now I am on 10.15.5 and it happens almost immediately every time computer goes to sleep so I am pretty sure it is sloppy Catalina code...

I tried that but it didn't work. (System Preferences -> Notifications -> Do Not Disturb -> Turn on Do Not Disturb and check "When the display is sleeping.")

Are there other settings that could also help? My monitor is also dell s2718d.

The only thing that works so far is turning sleep off completely. I really hope apple comes out with a fix soon...

Just chiming in to say I have this same problem. It has gotten worse with 10.15.5. I was able to find some combination of settings on 10.15.4 which allowed me to manually sleep the Macbook Pro while connected to an external display. Now that doesn't work any more.

It's not just Dell monitors I think since I am using an Acer Predator X34 monitor and it still happens.

Same problem started 2 days ago with NEC monitor. Crashes every time it sleeps. Spent an hour with Apple today and in the end was left with "a fix is in progress" but did not know when. Tried solutions above with no improvement. Had this MBP 6 months without a problem, also running 10.15.5. I guess I will have to set for a long delay before sleeping and then unplug the monitor USB. Does not happen when disconnected.

Hy guys,

just to report that I have the same issue here. MBP 16 with 2 LG external monitors (bought at the Apple Store) daisy-chained with USB-C.

I had to stop using the MBP with the lid closed. I tried again today and after locking it, 2 min later, it crashed but this time, after the reboot I had an error message, which I never had before.

The message helped me find this thread actually.

I read in the comments that a fix is on its way... I guess we'll have to wait for it then !

In the mean time, I'll try the solution suggested earlier about the settings in the "Do not disturb" section.

I hope we'll have this issue fixed quickly !

Same issue, along with failed time machine backups to a network drive (smb) and glitches on webkit apps (chrome, brave, some apps) after waking up, that require reboot. All of these started to happen in the last couple of updates.

Please fix. We pay a premium for these machines. There's a reason I'm not buying an acer machine with windows. Fix now.