I am doing a clean install of Mojave on my MacBook - it has simply not been possible to upgrade from High Sierra to Mojave automatically. I understand that it will overwrite all of the HDD contents I know I can simply copy document files etc and then copy them back into the new system But, will a Time Machine backup from the original High Sierra be able to reinstall all of my programs?

  • Why can't you upgrade automatically. This problem might affect the answers.
    – mmmmmm
    Commented Jan 30, 2019 at 1:24
  • I have tried to upgrade three times; got a different error message each time and went into a restart/upgrade failed/restart loop which I had to resolve with recovery from my Time Machine backup. The three errors were error 7E7AEE96CE com.apple.diskmanagement error -69854 com.apple.DiskManagement error -69874
    – robfuscate
    Commented Jan 30, 2019 at 2:08
  • A MacBook (not a MacBook Pro) that fits a hdd might not be able to run Mojave, are you sure your system is supported? Commented Jan 30, 2019 at 4:28
  • It's a 2015 MacBook Air - and besides that, if Microsoft updates can say 'this nupdate is not suitable for this machine, then surely Apple updates with their locked down architecture can too
    – robfuscate
    Commented Jan 30, 2019 at 6:00

3 Answers 3


Thanks for the help. The problem turned out to be both more complicated and simpler than I originally thought.

I had installed a Tar Disk in 2015 and more research showed that quite a few users were having the same problems and error messages as I was.

I followed the instructions here - https://www.tardisk.com/pages/uninstall-sierra - to uninstall the Tar Disk - NOT removing it because I was coming from High Sierra, as the instructions said. It DID NOT solve the problem.

I then went through the whole rigamarole again; shut down my MacBook and physically removed the Tar Disk. I then reopened the Disk Utility and reformatted the internal Mac SSD - installed Mojave from a USB and it seems to have worked.

To answer my PRECISE question - now that Mojave is installed - Time Machine has been able to recover/reinstall all of my files and programs

Thanks again to those of you who responded


Though your proposed solution may not actually get to the root of this issue, assuming you can successfully install a fresh Mojave OS onto your machine...

Yes, a Time Machine backup can be used to Migrate to a newer macOS. The only difficulty would be if you try to Migrate to an older one.

Perform the Migration immediately at first signup/login to the new OS. If you do it later, you will end up with two accounts rather than one simple migration.
Theoretically, you should end up with essentially the same as if you had just done the update the regular way, all apps, prefs, docs exactly as you had them.


If your nervous about depending on Time Machine backups you should consider that Carbon Copy Cloner might be your best simple solution.

It will let you go into the weeds and grab the files that are relevant when transitioning OS versions and disk formats (HFS+ vs APFS).

Time Machine is great for those weekly backups in case your disk suddenly dies, but CCC is the advanced route that gives you the flexibility and options you might need (I just did a Mojave back to High Sierra restore combined with APFS back to HFS+ with CCC).

https://bombich.com/kb/ccc5/everything-you-need-know-about-carbon-copy-cloner-and-apfs https://thesweetsetup.com/apps/best-app-for-bootable-backups/ https://www.maketecheasier.com/create-bootable-clone-of-mac/

Just make sure that your not running into any problems because of going between a case-sensitive & case-insensitive disk format.. but https://github.com/cr/MacCaseSensitiveConversion will help with that :)

  • Thanks .... I haven’t been able yet to clean install Mojave, so that’s my first thing to eal with, but you have answerer my question
    – robfuscate
    Commented Jan 31, 2019 at 4:31

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