Mac – Restoring Catalina timemachine back-up to Mojave

backupcatalinamojavetime-machine

I have read a few posts and answer but I am not quite sure…

I was on Catalina and for multiple compatibility reasons, I need to go back on Mojave. I did a time machine back up on Catalina, erased the startup disk and Mojave (which my Mac was shipped with) is now installing. What is going to happen when I restore from my Catalina time machine backup?

I don't want the OS restored. I want everything I had on Catalina switched to Mojave.

Best Answer

If you already have the system software installed, time machine will install your personal files and the files you select. It will not install the system software.

See this answer for more detail.

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Mac – Restore previous-released OS version(mojave) from catalina public beta

Unlike some installations of some operating systems there is no OS level uninstall feature in macOS.

That is true for applications, though some do have uninstallers available.
That is true for minor OS version upgrades, EG 10.14.1 to 10.14.2
That is especially true for full versions, EG 10.14 to 10.15

What that means is that if you install an OS update or upgrade and you need to revert back to the previous version there is no built-in way to do so.

In fact the ONLY way to revert any OS upgrade is to back up your files, boot into recovery mode (or a bootable USB installer), wipe the drive and re-install the operating system. Once that is done you can restore from your backup.

Find date of upgrade from Mojave to Catalina

For me, the most direct route to get software update information is using Terminal and the softwareupdate command, e.g.:

softwareupdate --history

To filter for macOS Catalina, use e.g.:

softwareupdate --history | grep Catalina

As shown in the output from my system:

$ softwareupdate --history | grep Catalina  
macOS Catalina                                     10.15      10/08/2019, 07:24:17  
$

You can also use softwareupdate -h to output the internal help. or use man softwareupdate for its manual page.

Best Answer

Related Solutions

Mac – Restore previous-released OS version(mojave) from catalina public beta

Find date of upgrade from Mojave to Catalina

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