I have one of those MacBook Pro's (2015) with the hardware fault which causes frequent spontaneous shutdowns.

The problem can be solved by renaming or deleting AppleThunderboltNHI.kext which I have done after every MacOS Catalina update for the past couple of years, basically everything except step 7 & 8 below.

In Big Sur, the change doesn't "stick," the AppleThunderboltNHI.kext file is restored automatically after restarting in normal mode, so I have followed the procedure which works according to many on the discussion referenced below.

Everything goes okay unless I do step 8, at which point the MacOS will not boot, I get a message like "...was restarted because of a problem..."

The only thing that seems to fix that, is to reinstall Big Sur from recovery mode, which does work. But then the AppleThunderboltNHI.kext file is restored.

I suspect that something in step 8 is causing this procedure to fail somehow but I am not at all familiar with using "snapshots" or the "bless" utility. So I'm hoping someone might be able to help me solve it.

Note: The following instructions are not mine, and I am not recommending them as a solution.

https://developer.apple.com/forums/thread/666567?answerId=646500022#646500022

Posted by sf98723

Follow this procedure :

1. Reboot in rescue mode (reboot while "Cmd + R")

2. csrutil disable

3. csrutil authenticated-root disable

4. reboot in rescue mode

5. mount -uw /Volumes/[MacOS ]

6. 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)

7. REBUILD the extensions cache ! (new has-to-do in Big Sur...) : kmutil install -u --force --volume-root /Volumes/[MacOS ]

8. DON'T FORGET to create another system snapshot to take these modifications under account at next reboot : bless --folder /Volumes/[MacOS ]/System/Library/CoreServices --bootefi --create-snapshot

9. csrutil enable (mays be you have to reboot in rescue mode.. not tested)

10. Finally, reboot in normal mode

I have one of those MacBook Pro's (2015) with the hardware fault which causes frequent spontaneous shutdowns.

The problem can be solved by renaming or deleting AppleThunderboltNHI.kext which I have done after every MacOS Catalina update for the past couple of years, basically everything except step 7 & 8 below.

In Big Sur, the change doesn't "stick," the AppleThunderboltNHI.kext file is restored automatically after restarting in normal mode, so I have followed the procedure which works according to many on the discussion referenced below.

Everything goes okay unless I do step 8, at which point the MacOS will not boot, I get a message like "...was restarted because of a problem..."

The only thing that seems to fix that, is to reinstall Big Sur from recovery mode, which does work. But then the AppleThunderboltNHI.kext file is restored.

I don't know is causing this procedure to fail. So I'm hoping someone might be able to help me solve it.

Note: The following instructions are not mine, and I am not recommending them as a solution.

https://developer.apple.com/forums/thread/666567?answerId=646500022#646500022

Posted by sf98723

Follow this procedure :

1. Reboot in rescue mode (reboot while "Cmd + R")

2. csrutil disable

3. csrutil authenticated-root disable

4. reboot in rescue mode

5. mount -uw /Volumes/[MacOS ]

6. 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)

7. REBUILD the extensions cache ! (new has-to-do in Big Sur...) : kmutil install -u --force --volume-root /Volumes/[MacOS ]

8. DON'T FORGET to create another system snapshot to take these modifications under account at next reboot : bless --folder /Volumes/[MacOS ]/System/Library/CoreServices --bootefi --create-snapshot

9. csrutil enable (mays be you have to reboot in rescue mode.. not tested)

10. Finally, reboot in normal mode