MacBook Pro 15" (2016) Crashing while connecting/disconnecting the LG 5K Monitor

Update to my previous comment:
I went to the Apple store to test an identical LG 5k display with my own MacBook and it worked without any issues. Likewise, I asked one of my friends to come around to test my monitor with his MacBook and the outcome was the same. My monitor didn’t switch on and it also crashed my friend’s MacBook. I can safely conclude that in my case the fault is in the monitor. I contacted LG and they refused to take the monitor in for a fix. Also, since the problem doesn't seem to be with the laptop, Apple won't be able to fix it either. I contacted an LG partner that deals with fixes and they told me that the problem is most likely in the monitor's mainboard. They suggested to replace it and charged me £360 including pickup and delivery. It's expensive. Should I go for it?

UPDATE 2 - NO CRASHES AFTER 3 DAYS OF COMING BACK FROM APPLE CARE - Replaced logic board, 2 x IO boards and cables..

I have been using with Dell curved 4K Monitor at work and dual dell non-4k at home (one HDI and other DP)

My 2016 MBP with Radeon 460 has not crash in 3 days.

I've continued to do sleep, open clamshell, unplug monitors, re-plug monitors, etc. etc. in various combos of clamshell closed and opened..

I had one small glitch this agternoon where the top right (where the time is) had a red bar.. but I unplugged to monitor and re-plugged it and it went away..

So far no crashes.. And no more "Red and Yellow" screens.. (Prior it used to crash on pretty much all of the above actions)

I had same problem, MacBook frozen every morning requiring a hard reboot. I solved this by replacing LG’s included black thunderbolt cable with this cable that Apple just released: https://www.apple.com/shop/product/MD861LL/A/apple-thunderbolt-cable-20-m

The issue has been resolved. Either by Apple directly with a software update (running OS X 10.13.2) or by myself as I'm now using Startech and A-logic USB-C cables as opposed to the cables that came with the 4K monitors that I use from Dell and Acer. It has not crashed - unless I accidentally make a mistake in the sequence of connecting / disconnecting it with the external monitors.

I think (hypothesis) that the issue with the laptop crashing is due to how the OS handles the power / signalling with the external monitors that it gets confused and crashes unless you follow sequence when connecting / disconnecting.

When the laptop is connected to an external monitor and the user wants to disconnect it from the external monitors, either to transport it (go to work) or to use it independently then they'd need to do the following.

1) If going to work, and the laptop is to remain in clamshell, - then put the machine to sleep BEFORE turning off the external monitor or disconnecting the cable.

2) if you plan on working with the laptop directly after disconnecting it from the external monitor. Then, open the laptop screen from clamshell, - make sure that it is working fine, - then disconnect the external monitor.

If you've returned from work and want to connect it to the external monitor. Either keep the laptop in clamshell, connect the cables, then turn on the monitor and bluetooth / wireless keyboard mouse and wait for it to send a graphics signal the monitor. If nothing happens, - then try opening the laptop screen to see if the laptop screen has your login details, etc.

I think (hypothesis) that the crashes were an issue with the OS - Graphics card - power management. If the laptop had been in clamshell - connected to external monitor. And you just disconnect the monitor, - the OS would believe it needs to go to sleep - it had just lost power, and if you then open the laptop screen directly. It would crash. Similarly when connecting the laptop to the external screen - it suddenly starts to receive a signal and it is trying to identify the accessory now connected to it.

Acer / Dell, and non-Apple hardware monitors have pretty basic accessories that do not have power management / communication chips in them to communicate with the computer. When a windows laptop connects to these monitors - they would work fine - as the OS is built to handle them. However, when it comes to an Apple laptop, - they require / expect the accessories (monitors) to have some sort of advanced - power management / signalling in them.

Also, its worth noting that the Dell / Acer etc monitors, are not Thunderbolt 3 monitors, - that they are a DP monitor with USB-C input interface labelled as ALT-DP. A thunderbolt 3 monitor would have the power management chip that I mentioned.

My laptop now does not crash - as long as I'm following the right sequence, and it automatically crashes if I don't follow the sequence. Feeling a lot better that I understand how to avoid crashes to not lose my work.

UPDATE - NO CRASHES AFTER 2 DAYS OF COMING BACK FROM APPLE CARE...

No chrashing so far after sending in to apple Care and them replacing logic board, 2 x IO Boards and cables.

I've done sleep, open clamshell, unplug monitors, re-plug monitors, etc. etc. in various combos..

Crossing fingers - So far so good...

So far, my machine has been running for 12 days and 10.30 hrs without a crash. Its running 10.13.3. File Vault is OFF; Touch ID is ON.

[November 2017, the logic board was replaced, due to continuous crashing]

The approach that I've taken is,

- When I want to connect the MBP to the monitor. I place it in sleep mode (by selecting the option Apple-Menu - Sleep) not just closing the clamshell and connecting immediately. There has to be a few minutes between the laptop in sleep mode and making that connection. Then I would connect the monitor, turn the monitor on and press the keyboard - move mouse to wake it up.

- When I want to disconnect the MBP from the monitor. I place it in sleep mode, wait for the screen to be searching for a signal; then I would disconnect it. I would open the lid a few minutes later to continue working.

I haven't opened the laptop while it's connected to the external monitor; nor have I tried to connect the laptop while the lid is open to the external monitors. I also close any memory intensive / CPU intensive applications before connecting / disconnecting. Photoshop, VM-Ware and Matlab are closed always prior to connecting / disconnecting it.

There are times when the laptop is just connected to the USB-C monitor, it doesn't wake up / display anything on the external monitor; I would then turn on the second monitor that is connected on DP - and that works always. I would login to the computer then unplug the USB-C monitor and replug it then it would work fine. Last point, when I want to walk away from the computer and would want to switch off the monitor; I would place the machine in sleep mode, then once I see the screen is looking for a signal, I would turn off the monitor.

I've become quite aware of sequence - approach to avoid any potential failure - crashes in the laptop. An extra 30 seconds or a couple of minutes while doing something silly is a lot easier than it crashing - myself worrying about losing data and then having to run disk-checks and re-open everything.

I disagree,

After updating to 10.13.2 I connected to both an LG 5K and an Apple thunderbolt monitor and was able to replicate in both instances the freeze by opening the clamshell. This was performed with the 2016 MBP w/touchbar and AMD Radeon Pro 460 GPU.

Something extremely interesting is that I did the same test with a 2017 MBP w/tb with Radeon Pro 560 and didn't freeze!

I documented this in a multiple videos and forward them to Apple. The GPU in the 2016 MBP is the problem.

Rob, I took my laptop to an apple store and froze. Thus far I have tested 4 different LG 5K monitors and 2 different 2016 late MBP with 460 GPU and crashed in every combination.

Even Apple confirmed to me yesterday that that reproduced the problem.

An important thing to do is to set you resolution, both laptop and monitor, to maximum (both while clamshell is open and when is closed. This results in certain freeze when you open the clamshell.

I assume your MBP has the AMD Radeon Pro 460 GPU?

The 2016 model. I bought a 2017 and held on to it for a couple of weeks to trial it. and it had crashed as well, so I returned it and held on the 2016. If the 2017 did not crash, then I would have held on to it and sold off 2016 to someone that doesn't need to connect to an external monitor.

Perhaps something to consider. Is your laptop SSD encrypted or unencrypted. When I had the hard drive encrypted, - it crashed 9 out of 10 times with an external screen and the machine being in clam-shell connected to a bluetooth keyboard. I rebuilt the machine without an encrypted drive, and along with the sequence approach to connecting / disconnecting to an external monitor. the laptop uptime is now more than 4 days. The last time it was restarted was when the OS X update came out. I generally do not restart / shutdown the machine. Oh, and I replaced the monitor cables to Startech and A-logic. I learned to avoid the original monitor cables.

Great!!! Thank you so much.

Please find below a video I made showing the problem.

MacBook Pro 15" (late 2016) Crashing while connecting/disconnecting external monitor. - YouTube

We tested two 2016 (late) BMP with 3 different LG 5K monitors and one Apple thunderbolt monitor and the problem was present at any combination (AMD Radeon Pro 460). Additional 3 replacement MBPs 2016 had GPU issues.

We also tested the 2017 BMP with LG 5K with no issue (AMD Radeon Pro 560)....

All tests with High Sierra

Yousef, I got 3 replacements (late 2016 MBP) and all had the same problem. This is not an isolated issue. When I used the 2017 MBP I didn't have a problem with LG 5K. I guess the problem is the AMD GPU.

See the following video:

MacBook Pro 15" (late 2016) Crashing while connecting/disconnecting external monitor. - YouTube

In my tests I didn’t have a problem with that 2017 MBP with the 560 GPU.

The test I did was with the 5k LG and opening the clamshell.

I also tested several 2016 MPB with the 460 GPU and all had the problem.

See the video I posted.

MacBook Pro 15" (late 2016) Crashing while connecting/disconnecting external monitor. - YouTube

Did you have any CPU intensive / memory consuming applications open at the time? I used to have the crash - red / yellow on the screens - whenever I was running Matlab or photoshop - then connected a screen or disconnected the screen.

At present, I close any application that may be using the CPU or memory intensively. I even close the virtual machine before making the connection / disconnection to the monitor; and I follow a sequence when connecting / disconnecting the monitor. I think thats why I haven't had any crashes, and that they've managed to improve how OS-X handles the changes in power consumption as a result of having an external monitor.

The challenge that the Apple Care rep once said to me - during a 2 months troubleshooting escapade - is that they don't know whether it's the Radeon Pro 460 - the logic board; the Applications that I am running; or the I/O ports. Also they are two different problems being faced, - 1) is the sleep / wake failure that occurs as a result when the machine is connected with an external monitor; 2) Connecting / disconnecting it from an external monitor.