Touch Bar Does not work after upgraded to Big Sur 11.4

Hi truongv, 

Welcome to Apple Support Communities. We understand that you're having an issue with the Touch Bar on your Mac after upgrading to Big Sur. We'd like to help. 

Do you notice that this happens when you use a specific spot on your Touch Bar? Are you trying to expand your Touch Bar in Settings when this happens? 

Does this issue persist in safe mode? Try that and let us know: How to use safe mode on your Mac

Let us know some additional details and we'll go from there. 

Take care!

truongv wrote:

No, I was not using any specific spot of the Touch Bar or messing with the Touch Bar settings. So far, this happened after the MacBook woke up from sleep. I will the safe mode suggestion next time.

For the Intel Mac— sleep/Touchbar issues try resetting the SMC https://support.apple.com/en-us/HT201295

if no resolve

Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379

truongv wrote:

Reset NVRAM/PRAM also didn't work. The problem is back this morning (2 days).

If resetting the SMC and NVRAM does not sort the issue then you most likely are looking at a hardware issue.

In or out of warranty you can get a free over the counter 'Apple Service Diagnostics' test /assessment

Make an appointment for a "hardware issue"

https://www.apple.com/retail/geniusbar/

Outside the USA

https://locate.apple.com/country

From iOS device using the app to make a online Genius Bar appointment is easy: 

https://itunes.apple.com/us/app/apple-support/id1130498044?mt=8

(note: due to the temporary closure of Apple Stores and the staggered reopening there may be some delays.

 ref: https://www.apple.com/shop/browse/store/temporary_closures )

 “Mac notebook, contact us and we'll send you a box you can use to ship it to an Apple Repair Center. We'll return your repaired product to you as quickly as possible. Depending on where you get service, you might be able to check the status of your repair online.”  Start a service request https://support.apple.com/mac/repair/service

Call Customer Support  (800) MY–APPLE (800–692–7753)

or on line  https://getsupport.apple.com/

or call  AppleCare Support at 1-800-APLCARE (800-275-2273)

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

https://support.apple.com/en-us/HT201232

Learn how to get your Mac fixed and how much it will cost. 

 https://support.apple.com/mac/repair/service

 Get your Mac ready for service - Apple Support   https://support.apple.com/en-us/HT209095

Yes, since I upgraded to the BS11.4 we too have had this issue in a number of our machines. There is neither rhyme nor reason to the reasons the Touch Bar stops working. It just goes dark. Sometimes, it is after re-opening the MBPro, or sometimes mid use with Excel or Safari, or Word.

Just makes no sense.