Run Time Machine recovery from bootable USB - what if MacOS installer on USB drive is earlier than my backup

[GH1852]

First, the only reason I am asking this question is for a friend in a rural area whose download speed is 6.0 Mbps.


I am not trying to do this at the moment, but I'd like to know for future use. Suppose I create a bootable USB installer, using Mac OS Monterey 12.7.1. In 2 months, I want to use the USB installer to undo a problem. Boot from USB, click on Restore from Time Machine Backup. It warns that it will erase the destination drive.

1) Will it then go ahead and install MacOS from the USB drive - NOT an Internet 5 hour download from Apple?

2) If it is aware that my backup was made when I had a future MacOS - say Monterey 12.7.5, will it download the delta updater so that there aren't problems with the Time Machine restore?

I am aware that when using Migration Assistant, one needs to update MacOS to meet or surpass the version of the backup.



Thanks in advance for taking a look

 

[DarkPremiumCho]

1. Yes it will install from the USB.
2. No, it will instead refuse to restore. (IIRC, just like a newer backup refusing restore to a device with older iOS)