If you installed the Big Sur 11.6.1 Update, Recovery OS will be upgraded Monterey on your M1 Mac.
Normally when you install a macOS update, recovery gets updated so it matches the OS version.
Example: You have an M1 Mac that has Big Sur 11.5.2 on it. Then you installed the 11.6 update. The following happens.
M1 Mac
- MacOS is updated to 11.6
- Recovery OS is updated to 11.6
- Fallback Recovery stays on 11.5.2
Intel Mac
- MacOS is updated to 11.6
- Recovery OS is updated to 11.6
Big Sur OS and Monterey Recovery on M1?
MacAdmin @nstrauss first reported something strange last week.
https://support.apple.com/en-us/HT204904 Command + R vs Option + Command R. The OS that shipped with your Mac vs the latest available supported version. What’s the equivalent to this on Apple silicon? If I’m not ready to move to Monterey, but recovery is only offering Monterey, what can I do?
nstrauss
Wait what?
How could you have an M1 Mac with Big Sur installed but Monterey as the recovery OS?
There is one way you can get into this situation.
- Upgrade an M1 Mac to Monterey
- Boot to recovery with Big Sur USB Installer
- Erase the drive
- Install Big Sur
- You now have an M1 Mac with Big Sur OS and Monterey Recovery.
The only way to fix this is to use Apple Configurator 2 + DFU mode. You can restore macOS and Recovery back to Big Sur with the 11.6 IPSW.
This was not what happened in Nathaniel’s situation.
The Big Sur 11.6.1 update changed the normal process.
EDIT: This happens with ANY Big Sur update!
Example: You have a Software Update deferral in place. You are offered the 11.5.2 or 11.6 update, you will also get Monterey Recovery.
I started talking with someone who knows the recovery system very well. He was just as confused as I was.
I decided to test on my M1 that was on 11.6. I Booted into recovery, and recovery OS was on 11.6. Then I booted into fallback recovery and it was on 11.6.
The version was 11.6 because I used AC2 and the 11.6 IPSW to restore.
I then installed the 11.6.1 update in System Preferences > Software Update.
When the update was complete, the OS was on 11.6.1. I then booted into recovery and found this.
Recovery is on macOS Monterey 12.0.1 …. ok
Let’s try Fallback Recovery. If you are not familiar with FBR this is what Apple says about it.
Fallback Recovery = From a shutdown state, double- press and hold the power button. The same process as recoveryOS boot, except that it boots to a second copy of recoveryOS that is kept for resiliency. However, LLB doesn’t lock an indication into the Boot Progress Register saying it is going into recoveryOS, and therefore the fallback recovery OS doesn’t have the capability to change the system security state.
Apple Platform Security
The idea here is FBR is a 2nd copy of recoveryOS that is one version behind. This a great troubleshooting tool that you could use if you installed an update but something went wrong.
So I booted into FBR and it was on 12.0.1 Monterey.
How can you confirm that you are booted to FBR? From the Apple Security Guide, you should not be able to modify system security.
Once in Fallback recovery, I attempted to modify the Startup Security Utility and got the message above.
Howard Oakley wrote an excellent article on Fallback Recovery if you would like to learn more.
eclecticlight.co/2021/02/20/m1-macs-have-another-hidden-boot-mode/
More Testing
We now know that installing the 11.6.1 update will update recoveryOS to Monterey. What about the Big Sur 11.6.1 full installer?
1st test – 11.6 installed = 11.6.1 Full Installer
After using the 11.6.1 Full installer, macOS recovery will be updated to Monterey 12.0.1
2nd test – 11.6 installed – 11.6.2 Beta Update
The update showed up in system preferences as a full 11GB update. After updating, recoveryOS was Big Sur
3rd test – 11.6.1 installed – 11.6.2 Beta Update
Maybe the issue was just in the 11.6.1 update? After installing the 11.6.2 Beta update, recoveyOS was on 12.0.1 Recovery. You would think that the 11.6.2 Beta update would have installed 12.1 Beta recoveryOS but that was not the case.
If you still need to Reinstall Big Sur.
This is where the new M1 Recovery system comes in handy. All you need to do is create a Big Sur USB installer.
- https://support.apple.com/en-us/HT201372
- Boot to M1 Boot Picker by holding down Power.
- Select Install macOS Big Sur.
- You are now in recovery and can use the Big Sur USB installer to reinstall macOS Big Sur.
Conclusion
So what is the deal with this situation? We have a few possibilities.
- This is a bug or mistake on Apple’s part. This is unexpected behavior that we have not seen before.
- There is a technical reason behind the change.
- Apple wants users to upgrade to Monterey when reinstalling macOS.
I’m not pointing in any one direction because I don’t know why this is happening.
I’ve submitted a ticket to Apple Enterprise Support to find out. I will update you when I hear back.
Thanks
Hat tip to someone who reached out to help clarify the situation.
2nd hat tip to Howard Oakley, Mark Buffington and Pico for additional confirmation plus answering some of my questions.
