Sleep transition timed out after 180 seconds while notifying clients about upcoming system capability changes.

True that. I was also told that it's an issue that had been reported by many users/purchasers. I mentioned to the Customer Care agent that for the money spent on these things, one would expect that it would work first time every time?!

exact same new MBP 16" happened straight outta the box,

called Applecare, advised of the usual SMC reset, NVRAM reset if issue persisted to reinstall the Mac OS. All which I did and issue was still there. Not happy as its a brand new machine. Aftersales sent me a replacement, which I've set up last night. And the EXACT same issue. Not much point in sending this Mac again as it seems such a common thing. I'm as well to wait it out. I'm not setting up another machine from scratch. I didn't restore from the previous MBP set it up entirely as a new device.

panic(cpu 2 caller 0xffffff800d091b2c): Sleep transition timed out after 180 seconds while notifying clients about upcoming system capability changes. Suspected bundle: com.apple.iokit.IOGraphicsFamily. Thread 0x74.

To everyone who has this issue: it is true, the issue is present, however, disabling power nap, as described on the first page of this discussion, does the trick. The root issue may or may not be resolved in this version of MacOS, so I chose to simply disable the power nap and in the two months since I’ve done it there weren’t any crashes.

You may want to try that as well. :)

I'm not sure that simply disabling Power Nap is a viable workaround. I've disabled it plus all the other fancy sleep/hibernate features and just gone back to a plain old sleep with no sort of session writing to disk (meaning if it crashes, i reboot and start again fresh—which I'm fine with).

Point is, even with Power Nap disabled along with the other stuff, the machine still crashes 180 seconds after going to sleep when connected to an external display. MBP 16".

Note: mine did not always do this. I can't recall when, exactly, this began. Maybe Catalina?

Same here. My brand new MacBook Pro 16" was running macOS Catalina 10.15.5 out of the box and it had the sleep issue from the moment I started using it before I had even installed any other software. I ultimately turned off PowerNap, as others suggested, and that did the trick. But this is clearly a widespread bug that Apple needs to address with the next release.

I can confirm that this issue was occurring with 10.15.4 which was pre-installed on my new macbook, but I can also confirm that updating to 10.15.5 has NOT fixed the issue. The only solution so far seems to be disabling the Power Nap option.

Yes, disabling Power Nap does not always solve the problem. I’m connected to an external Dell display, via DisplayPort.

And updating to the Big Sur beta did not fix the problem as well, which was quite disappointing.

I have same issue on my macbook pro 13 2020 higher end model. Final cut pro also crashes so many times... I have been Apple user for last 20 years and this is the first time to experience this level of disappointment. Is this end of Apple era?

same issue here, on a brand-new MBP 16".

Yep, same for me. Brand new MBP 16".

8GB GPU.

I haven’t tried unplugging before sleep because that’s inconvenient for me, but disabling power nap has worked so far (2 days)

The person I talked to said it was likely software and that they’re aware, so a fix is almost certainly in the pipeline.

As a workaround, it seems to be sufficient to go to System Preferences > Energy Saver and disable Power Nap. I did not find any of the other suggestions above to be necessary.

Same here. I've still been charging while my MBP 16" sleeps.

I also have this issue at least once a day, brand new MBP, 2 weeks old. Sad. Any word from Apple on fix?