Tuesday, March 26, 2024

How to Recover macOS Recovery

Howard Oakley:

Rarely, the Recovery volume becomes deleted, or the secure disk image it should contain gets removed. Unfortunately the only means of restoring it is to perform a macOS update, and even then some Macs seem unable to recover Recovery without the boot volume group being deleted and installed from scratch, best performed when booted from an external disk. Unfortunately, on Intel Macs with T2 chips, you might need to enable that using Startup Security Utility, which is, of course, only available in Recovery. You may now scream if you like.


When the Paired Recovery system on an Apple silicon Mac is updated in a macOS update, the Recovery system from that should be copied to the Recovery volume on one of its two hidden containers, named Apple_APFS_Recovery. In the past, that process has been unreliable, but Apple has improved that, and your Mac should now have a good chance that Fallback Recovery is available. Apart from Fallback Recovery being older than your current version of macOS, it also doesn’t offer the Startup Security Utility, so can’t be used to change Secure Boot settings, its major disadvantage.


If neither Paired nor Fallback Recovery are available, the best way to restore them for an Apple silicon Mac is to put that Mac into DFU mode, connect it to another recent Mac using a USB-C charging cable (not a Thunderbolt cable, which won’t work), then run Apple Configurator 2 on the other Mac. In that, download the current IPSW image and use that to refresh the ailing Mac’s firmware.


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The Mac used to stand out as the simplest platform for managing boot volumes. I'm sure a lot of technical details were managed "under the hood" but from a user perspective it was very simple to create and clone bootable volumes. It rarely didn't "just work" and when you had problems typically running "bless" would do the trick.

That's all gone now.I deeply appreciate the improved security of encrypted volumes and sealed partitions, but the ability to control your boot volume is effectively gone for me—I know it's there in theory, but I genuinely don't have the time to read and absorb all of Howard Oakley's posts just to use my Mac.

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