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User profile for user: xinchao1987
xinchao1987 Author
User level: Level 1
10 points

System crashes whenever external 4K USB-C monitor plugs in

Hi,


I have a Macbook Pro 15" with touchbar (purchased 2017). I have been using it with two LG 27UD88 4K monitors (USB-C on both ends). Starting from today, whenever I plug in the monitor the system immediately freezes, mouse, keyboard all lose responses, and I have to restart. If the monitor is plugged in before starting, the system just keeps crashing and restarts and i cannot even see the login page.


This was working all fine before this morning. Yesterday I just left the Macbook sleep with two monitors connected (what I do everyday). But this morning the problem starts to happen. I looked into the update history and the most recent update was iTunes 12.7.2 update on Dec 7th.


Another thing I realized is, I cannot reset my nvram. Followed the apple steps, the monitor lights up, then turns black, and lights up again, but the system just doesn't start unless I release the key combinations.


Anyone runs into the same issue?

MacBook Pro TouchBar and Touch ID, macOS High Sierra (10.13.1), null

Posted on Dec 8, 2017 5:05 PM

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1 reply
User profile for user: Teddy_B
Teddy_B
User level: Community Specialist

Dec 9, 2017 3:14 PM in response to xinchao1987

Hello xinchao1987,


Thanks for that info and choosing the Apple Support Communities. If I understand correctly, you are having an issue with using external displays with your MacBook Pro, even after trying some troubleshooting steps. You can figure out if unexpected behavior is related to a user file or setting by trying to reproduce the issue from another user account. This process includes creating a new user account, logging in to it, and testing for the issue.


How to test an issue in another user account on your Mac


Next, use safe mode to start up your Mac as it does the following things:

  • Verifies your startup disk and attempts to repair directory issues, if needed
  • Loads only required kernel extensions
  • Prevents startup items and login items from opening automatically
  • Disables user-installed fonts
  • Deletes font caches, kernel cache, and other system cache files


Log into your user account and test the issue while in safe mode and then restart normally and test the issue again.


Use safe mode to isolate issues with your Mac
Limited graphics performance in OS X recovery or safe mode


Cheers!
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System crashes whenever external 4K USB-C monitor plugs in

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