External Displays won't come back on

I had tried earlier similar measures with PRAM reset and changing the USB port. It seemed to work for a few days, but reverted back to the same problem eventually.

BTW, I suspect putting the system manually to sleep seems to improve the behavior, but don't have enough stats to say for sure.

Anyway, this problem is an abomination to have lasted this long and punishing us for having spent 1K+ $ for the LG 5K monitor when there was no other options.

All good info!

I had previously done the PRAM reset, although I'm not sure if I did the exact process that you laid out. I may give it a shot again. Thanks @Wayne

I did also get a formal ticket opened up with Apple this afternoon. I should get a follow up either Monday or Thursday depending on if results come in on Monday. They did a system capture and uploaded a few hundred MB of diagnostic data.

Also seeing this issue on a brand new 16” MBP with Radeon 5500M running 10.15.3. Purchased about a week ago.

When I plug and unplug the laptop to different monitors, for example in meeting room situations, the laptop will seemingly randomly stop working with external displays. When I go to plug in, the laptop monitor will start flashing on and off like it is trying to display to the external monitor but just gets caught in that loop and doesn't succeed.

Pretty wild to see this in a $4k pro halo product. Especially seeing that this thread has been going on for months.

I guess that’s just the state of Apple now. Not a big incentive to deal with pro users when the vast majority of their profits is from phones, wearables, services.

Mine crashed too. What a joke. I cannot believe what a POS this makes what is otherwise a very nice laptop. How could they possibly be unaware of this given the number of bug reports and service calls?

My only conclusion is that it is AMD’s fault or that apple just doesn’t ca re about how it’s flagship laptop cannot actually drive external monitors without crashing. Just saying that second part is insane.

BTW — the energy saver “hacks” do not work for me. The crashes still happen. It’s just a matter of time.

For me it is very surprising that Apple doesn't seems to have any system that catch these types of threads.

If they just has replied: "We understand that this is a problem and will look in to it. For progress information see ticket: 112341123"

It reminds me a little bit of politicians that cannot admit any wrong doing. Politicians that admit wrong doing scores goodwill and win in the long run.

I can live with hacks. No problems. As long that I know that Apple is looking in to the problem.

I will stay clear from 10.15.4

Sorry guys for this off-topic reply.

SO is it working for most people, I've seen a few posts where it's been crashing like mine is (see my previous post) or is it steady and not shutting down due to an OS crash after sleeping for a few hours?

If it's working for most, I'll try a clean install again I guess? Let's get a poll going, how many people did it resolve the issue for and how many people are experiencing crashes?

I also noticed, after installing 10.15.4, that the external display I have (LG 27") suddenly had switched over to a very vivid color tone. Tried playing around with it to no avail. Did a little research, and discovered that the new "High Dynamic Range" checkbox (see screen shot) seemed to be the issue. By unchecking it, the color has gone back to normal. (Disclaimer: I'm not a graphics pro, so I don't really know much about this, and maybe someone who does understands more about it and can tell you how to use the setting properly. I'm just telling you that for a layman user like me, unchecking it fixed the problem. :)

I use an LG UltraFine 5K, and so far ok. Used to have the same harsh color problem on occasion, but not since 10.15.4 update. [BTW, the UltraFine 5K doesn't show the "High Dynamic Range" checkmark in Settings...]

When it wakes from sleep -- as opposed to crashing -- it seems to work the way it should. I have both the LG Ultrafine display and an older apple thunderbolt display (using adapter) plugged into two of the MacBook Pro 16" usb c ports. But it has crashed 2X since the upgrade.

That’s great, I’m really happy everything is working on your end. But I just don’t understand how a lot of people on this post are getting crashes. I even did a fresh install did not put any apps on there, and had and had 10.15.4 on there and it would continue to crash with a fresh in style without me touching out at all. I did restore from Time Machine afterwords and restored my data. But this needs to be addressed and I don’t understand how some are working and yer some are crashing .

If anyone has any ideas please share.

Agree, this issue haas been going on for months now, and it not a small issue. I'm getting fed up dealing with it if I'm honest. Not too sure where the Pro part is in these laptops anymore. Windows 10 is looking better and better every year.

I've tried this for a couple of days with success so far. Fingers crossed. I had only done the "Prevent computer..." option and haven't seen much difference when unchecking "Put hard disks to sleep..."

It is always my Thunderbolt display, monitor #2 that doesn't come on. The LG, monitor #1 does wake from sleep (as well as the MB display, #3). I've taken to shutting down all of my apps in case the computer crashes, though I've had fewer crashes the last several days. I think 3 since 10.15.4.

Same Problem, just got new MBP 16 which was working great. It works with new LG 5K display that arrived yesterday great. Lasted one day. Now it crashes shortly after sleep - Panic attack as other have reported. This problem appears to have been around for years. Is Apple asleep? It seems like they don't even care.

Thank you for this advice - I will try that now as never had any issues with my other Macbook and after an hour on the phone to Apple who seem more clueless than ever these days i got know where - there response was unplug the screen and see if if crashes when its unplugged!