Do I need to have the original version of MacOS installed on my SSD in order to restore from a Time Machine back up?

[lkar]

I made a backup of a 10.13 machine, tried to upgrade to 11.5 with OpenCore Legacy Patcher, there were bugs in the new OS, so I needed to revert back to 10.13, but when I tried to restore it, it went through the Time Machine restore process, but afterwards it didn’t boot. What did I do wrong?

 

[rm5]

I made a backup of a 10.13 machine, tried to upgrade to 11.5 with OpenCore Legacy Patcher, there were bugs in the new OS, so I needed to revert back to 10.13, but when I tried to restore it, it went through the Time Machine restore process, but afterwards it didn’t boot. What did I do wrong?

Rather than doing that, reinstall High Sierra (10.13), and use Migration Assistant. What TM Restore through Recovery does is it copies all the boot sectors, too, which assumes that the OS is not running under OCLP and is natively supported. So just use Migration Assistant and you'll be up and running!

 

[lkar]

Rather than doing that, reinstall High Sierra (10.13), and use Migration Assistant. What TM Restore through Recovery does is it copies all the boot sectors, too, which assumes that the OS is not running under OCLP and is natively supported. So just use Migration Assistant and you'll be up and running!

I see, but if I do it your way, I would have to re-install an OS once, while if I restored directly from Time Machine then I would not have to reinstall an OS at all (the time taken would be used to do the restore)? (is that right? I have never done a time machine restore before)

One thing to note, before I clicked restore, I didn't use disk utility to wipe the SSD to remove 11.5 (instead I restored right over it, in hindsight that might have been a mistake), my question is:

What if I had used disk utility and erased everything on that SSD and then restored using time machine from my portable HDD, then would i have been able to restore my computer without first installing 10.13 from the installer usb drive?

 

[iStorm]

I see, but if I do it your way, I would have to re-install an OS once, while if I restored directly from Time Machine then I would not have to reinstall an OS at all (the time taken would be used to do the restore)? (is that right? I have never done a time machine restore before)

One thing to note, before I clicked restore, I didn't use disk utility to wipe the SSD to remove 11.5 (instead I restored right over it, in hindsight that might have been a mistake), my question is:

What if I had used disk utility and erased everything on that SSD and then restored using time machine from my portable HDD, then would i have been able to restore my computer without first installing 10.13 from the installer usb drive?

The guide from Apple doesn't state to wipe the disk first, but it wouldn't hurt to try.

Recover all your files on Mac

If you use Time Machine to back up your Mac, you can recover your system’s contents if your system or startup disk is damaged.

support.apple.com

If that still doesn't work, then I'd suggest installing High Sierra yourself, and then restoring the files using Migration Assistant.

This is actually the method now for Big Sur, Monterey, and Ventura. Starting with Big Sur, Time Machine no longer backs up the OS anymore...so you have to reinstall it yourself. You can see how the guide is a little different if you switch to one of the newer OSes.

 

[gilby101]

I didn't use disk utility to wipe the SSD to remove 11.5

OCLP install will have modified boot partition, so you do need to erase the whole disk.

And, if it were me, I would install 10.13 (from a USB boot drive or from the internet) and then use Migration Assistant.

I hope your TM backup drive only has 10.13 backups. If it has been "upgraded" by running a newer TM, you could be in trouble!

 

[DarkPremiumCho]

No, if you have a full 10.13 backup. It didn't boot after the restore because the firmware settings were changed by OCLP. You need to reset the NVRAM and start over.