Time Machine restore: Big Sur 11.7.9 to 11.7.10 on iMac?

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Time Machine restore: Big Sur 11.7.9 to 11.7.10 on iMac?

Hi everyone,

I’m hoping someone can help me with an issue I’m having with my old iMac 27” (2014). Last week, the iMac suddenly failed: the Fusion Drives were no longer joined, so I had to install macOS onto an external drive to get it working again.

Now I want to restore the iMac from a Time Machine backup, but I’m running into a problem. My last backup was made on Big Sur 11.7.9, but the external SSD I installed macOS on has Big Sur 11.7.11. Time Machine won’t let me do a full restore and instead points me toward using Migration Assistant. From what I understand, Migration Assistant would only restore selected files and applications, and not create a complete replica of my iMac as it was before the failure. Is that correct?

I’ve tried to find a copy of Big Sur 11.7.9, but it seems to no longer be available. I have found 11.7.10, which is slightly closer to the version my backup was made on. From what I’ve read, Time Machine may allow a full restore onto that version, but I’m not certain. Does anyone know if restoring a backup from 11.7.9 onto 11.7.10 would actually work?

Any advice or guidance would be greatly appreciated. Thanks in advance!

Posted on Feb 18, 2026 9:21 AM

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Answer 1

Top-ranking reply

D.I. Johnson

Level 7

34,691 points

Feb 18, 2026 9:50 AM in response to dcbp

With the Release of macOS Big Sur, the OS is no longer backed up and a TM backup cannot be used to recover the Mac's OS (operating system). Time Machine does backup the user account(s) and some OS settings. Migration Assistant is the way to recover your user account, files and settings. Restoring data from an older OS to a newer one is what migration is all about.

If you have not already, you'll need to reinstall macOS Big Sur 11.7.11 on the iMac's internal drive.

How to reinstall macOS - Apple Support

When the reinstalled OS prompts you into the setup assistant, connect your Time Machine backup drive and select that as the source of your data when asked how you want to transfer your information.

Use Migration Assistant to transfer files to Mac - Apple Support

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Answer 2

den.thed

Level 10

92,254 points

Feb 18, 2026 9:41 AM in response to dcbp

1) You can migrate to a later macOS version using your TM backup.

see > Transfer to a new Mac with Migration Assistant

2) Time Machine only restores your files from the latest backup.

see > Recover all your files from a Time Machine backup

What you need to do is migrate from your TM backup during the initial 11.7.11 setup.

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