Big Sur - will not boot with Thunderbolt monitor connected

Same problem, using reinstalled Catalina which will only boot now if the Thunderbolt display is disconnected. Anyone know when this HUGE bug in Big Sur will be corrected?

same here, any news on fix in 11.1?

It took 3 months to fix the clock widget on ios14 to keep correct time.......not holding my breath for anything quick happening on this.

That's great to know. Now if I can get target display mode to work from my 2020 iMac to the 2012 iMac life would be great.

11.1 doesn't fix it for me. Still 2xchimes after reboot and then freezes with fans on.

I have 11.1 and still have reboot issues and camera, thunderbolt speakers and usb sockets on back of screen do not work.

Guys, this thread is called "Big Sur - will not boot with Thunderbolt monitor connected"

So once again: Big Sur / MacOS ver. 11.1 (just updated) DOES NOT fix the issue.

Happens to us all, I do hope you get your problem sorted.

I have the same laptop. do u face graphic issues like laggy dock and stuff

No more problems after installing the Big Sur update, everything works fine

I am having the exact same issue, I'm using Windows 10 with boot camp and the computer will not boot up with my thunderbolt display connected. I have to boot to the Mac OS and connect the display after. Windows will not recognize the display after it has booted making it unusable.

I have the same setup, same problem, this definitely was caused by the Big sir upgrade. Sadly I did a new install of Catalina and then a restore from time machine and the problem still exists. I know everything worked as I had just rebooted normally before the upgrade started. What is really strange is my Colormunki colorimeter I use to calibrate the monitor for my photography no longer works either. I see it power up but the software says it is not connected. It runs on the USB ports. I hope apple gets a fix fast as this shuts me down for what I do.

I have the same issue with a late 2013 MacBook Pro Retina.

Big Sur installed unattended with Thunderbolt display connected but I came back to a black screen.

It will now not boot with Thunderbolt display connected but boots fine without it and if connected after apple logo appears display works fine.

I believe Big Sur has delivered a firmware update as part of the installation which explains why the fault persists after I go back to Catalina.

I as well suffered the same. I rebooted the second trial of control/shift/option?/restart, and when it started in safe mode the screen turned a sickly yellow-green with black spots and a small orange box where the pointer should have been, I moved it around and there was speaking taking place. My computer was vulnerable, apparently. So I closed it down and turned off all WiFi in the house. That was last night. I removed bootable OSBS and the extra OSBS remained. Why 2? I downloaded during the automatic download, and decided to let it run the first time around, before I knew of the issues. I cleaned it up, and restarted in safe mode. Did the usual unnecessary but it feels good, removal of all superfluous items on my MacBook Pro 2019 retina.

It took a long time of being driven by fear, by anger and by logic. Thankfully, Logic is prevailing. Leave your computer turned off and charging. Do nothing until it is fully charged and holding when you unplug your laptop. Wait to see what is eating the computer, or cooking it in my case. The cooking/overheating has stopped and the fans have not kicked in. Apple must have heard us all and set about doing what we trust about Apple, to be the system we love and hate. Hopefully Love wins.

Wait. Set up things like Mail to your needs but leave Office or any programs alone, including Time Machine unplugged until we are all aware and able to see effective repairs taking place. Good luck all. As for the wacky screen when restarting, do not restart, just leave it plugged in with NOTHING running. Things should be approaching normality later today.

Tengo el mismo problema con el monitor externo Thunderbolt Display. En mi caso trabajo con un Imac 27" retina mediados 2015 i7 a 4GHz y AMD Radeon R9 M395. Enciende la pantalla y la externa sin problema. Cuando vuelve de reposo tras un tiempo de inactividad directamente se cuelga el ordenador para al minuto aparecer la pantalla de Panic Kermel.

Tras reinstalar el sistema, restablecer los arranques y hacer instalaciones limpias en tres ocasiones probé a desconectar e teclado, disco duro externo y finalmente el monitor Thunderbolt., resultado... es el monitor quien proboca el Panic Kermel.

Espero que Apple solucione pronto este fallo, no me hace mucha gracia la compra de otro monitor y menos sin saber si voy a tener el mismo problema

Suerte...