Ok. Found this working solution with Big Sur. Reboot in rescue mode (reboot while "Cmd + R") csrutil disable csrutil authenticated-root disable mount -uw /Volumes/[MacOS <your custom stuff here>] delete (or rename, or move elsewhere) the AppleThunderboltNHI.kext directory (I've moved all thunderbolt kext directories since I have no needs about this interface, but I think it works only by disabling AppleThunderboltNHI) REBUILD the extensions cache ! (new has-to-do in Big Sur...) kmutil install -u --force --volume-root /Volumes/[MacOS <your custom stuff here>] 7. DON'T FORGET to create another system snapshot to take these modifications under account at next reboot bless --folder /Volumes/[MacOS <your custom stuff here>]/System/Library/CoreServices --bootefi --create-snapshot 8. reboot (in rescue mode). This step may be unnecessary, not tested straight to 9. 9. csrutil enable 10. Reboot Enjoy. Cheers.. Here following step in other answer does not work for me, instead above step 6 works. Kmutil install -u --force --volume-root /Volumes/Macos (Enter WHATEVER YOUR MACOS DRIVE NAME IS, my macOS drive name is Macos)/System/Library/Extensions