Big Sur Won't Boot with Thunderbolt Display Attached

Several similar reports in this thread..

https://discussions.apple.com/thread/252038098

It looks like a bug in the firmware update that is In the Big Sur “upgrade”. Annoyingly, the firmware remains even if the OS upgrade is rolled back. There appears to be no safe way to roll back the firmware so I wait for a fix from Apple engineers in a future update... Hopefully, soon.

I have a similar problem. MacBook Pro (Mid 2014) won't complete booting with Thunderbolt Display plugged . In bootcamp windows side, the MacBook Pro did not recognize the Thunderbolt Display. I can not use the apple thunderbolt monitor in windows side.

Hello!

Same issue here with my MacBook Pro (late 2013) and Apple Thunderbolt Display.

When I boot the computer with the display attached to the MacBook, I get no apple logo, only the startup chime and then the MacBook starts repeating the chime and it won’t stop until I disconnect the display.

Also, have anyone noticed that the computer is running a bit hotter than before (under Catalina)? Now I get the fans firing up much more often.

Thank you!

I have the same problem. I already returned to macOS Catalina (TimeMachine), but the problem still appears. Also the genius bar in Apple Store can't help. It's a firmware bug. We have to wait for update by Apple, hopefully soon....

Hey,

my Mini (2019) boots with the cinema display (via Thunderbolt for USB-C) then looses all functions (USB Hub, audio ..). After reconnect it works - for a short while. I did not have that issue with Catalina - something queer with the thunderbolt support in Big Sur to my thinking

br --joe

Same issue here on a mid 2014 MBP with Thunderbolt Display plugged in. I hear the startup chime, but I get a backlit black screen with no Apple logo and no progress bar. If I shutdown the MBP, unplug the Thunderbolt Display, and restart, it boots just fine.

ALL SORTED...

I spent hours on the phone with Apple Ireland about this issue last week and they remotely took over my Macbook Pro and did loads of unfathomable tech stuff as I watched, including taking time-stamps of actions they did, as they occurred in real time.

They rang me to let me know that they were about to release macOS Big Sur 11.1 and that the engineers had inserted some coding to hopefully sort my/your issue.

They rang again tonight and asked me to download, install and restart to test it, and they waited while the install occurred etc.

And it works.... Macbook now happily reboots with Thunderbolt monitor attached, etc

Feel free to send me £10 notes in brown envelopes to show your eternal gratitude ;O)

Happy Christmas one and all.

Giles

Yes, very annoying and I hope they fix it soon.

Worked for me! So glad Apple sorted this out! The squeaky wheel gets the grease...