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OUM2303279 Author

Level 1

29 points

MacOS Big Sur, MacBook Pro 15 Late 2013, Thunderbolt Display

Following update to Big Sur, which also updates the firmware, my MacBook Pro 15 late 2013 will not boot if the Thunderbolt Display is connected. I can downgrade to Catalina but the firmware is not downgraded and the problem remains. I have reported it to Apple Support but wonder if anyone else is experiencing the same issue...

The system will boot correctly if the Thunderbolt Display is not connected

Connecting the display after boot the display works correctly on MacOS (which supports hot swop)

I use Bootcamp extensively and that does not support hot swop of the Thunderbolt Display so I

cannot use the display with Windows at all since updating (this is the big issue)

I have not found a reliable way of downgrading the firmware (which is where I believe the root cause of the issue lies)

Mike.

Windows, Windows 10

Posted on Nov 14, 2020 1:58 AM

Top-ranking reply

Donaldfromchippenham

Level 1

9 points

Posted on Nov 14, 2020 2:41 AM

Thank you. I'm glad I'm not alone or imagining things. I only wish I'd seen your post earlier!

I've had a very frustrating 24hrs trying to get Big Sur to work properly with my setup of MacBook Pro (Retina, 15-inch, Mid 2014) and 27" Thunderbolt display. The upgrade appeared to fail and booted to a black screen.

I reinstalled BS through (Command-R) and that didn't work.
I reset the NVRAM - no change.
Many restarts later, I discovered that it worked in stand alone mode when there were no external devices.
There were no issues with returning from sleep mode.
The Thunderbolt monitor works as normal but only if connected after MacBook has booted normally. On restart, boot will fail if still connected.

Many resets/restarts, shutdowns later, I have concluded that the issue is starting with the Thunderbolt display connected (and with it my ethernet connection and thunderbolt 2 connected Time Machine drive).

Since the Thunderbolt display is obsolete, I can't see Apple doing anything about its firmware. I hope they can find a work around as it's a pain having to reconnect every time.

I will report this to Apple as well.

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MacOS Big Sur, MacBook Pro 15 Late 2013, Thunderbolt Display

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