Time Machine and Migration Assistant to older Mac OS

[damiro]

Hello everyone,

I'm new to this forum, so please, excuse me if my post isn't in the appropriate section.

Here is the story: I have updated my MacBook Air (mid-2015) from El Capitan to Catalina and I'm not satisfied for various reasons. It seems that it is not possible to downgrade to the previous version without reinstalling everything.

I'm not concerned about transferring basic parameters, such as screensaver or recreating a user session on from scratch. But what I would like to know is: if I backup everything on Time Machine (on Catalina), then erase the MacBook and reinstall El Capitan, will I be able to restore all the Apps (and hopefully their parameters [I think of internet history and bookmarks, for instance]) and personal files (downloads, documents, desktop, etc) using Migration Assistant.

It should work, as it works when you get a new Mac, but I wanted to have some statements from professionals or experts who may have used that process effectively.

Thank you very much for your help.

 

[Longkeg]

It should work, as it works when you get a new Mac,

Not necessarily. TM is designed to go from a lower or equal OS to an equal or higher OS. When you buy a new Mac it will almost always have the latest OS pre installed. Remember, 99% of Mac help pages start with, “Make sure you’re running the latest version of Mac OS.”

If you try to back up an older OS with a TM backup created with a newer OS you’ll be greeted fairly quickly with an error message advising you to upgrade the older OS before you can proceed.

Apple doesn’t believe in downgrading and doesn’t make it easy to accomplish. But you can save many of those “parameters” in iCloud and they will be used for all your devices logged in to the same iCloud account. No need to restore anything as they live in the cloud not locally. Check out the Safari tab in the iCloud pane in System Preferences

 

[damiro]

Thanks for your answer. I really need to downgrade, as I can't wait for another update with a machine that is overheating and whose battery drains in no time, while everything was fine when running El Capitan.

I will try a backup on TM and also backing up on iCloud or external HD the old way.

I hope that I can copy and run most apps just by copying back the app folder on the newly installed OS, although I guess it won't work for all app. But let's hope it does work for the most used ones (mainly Office).

 

[Longkeg]

I hope that I can copy and run most apps just by copying back the app folder on the newly installed OS, although I guess it won't work for all app. But let's hope it does work for the most used ones (mainly Office).

If they are Apps purchased from tha Mac App Store it’s best to just download and install fresh copies. As long as the Apple IDs match up you can do this endlessly.

 

[damiro]

If they are Apps purchased from tha Mac App Store it’s best to just download and install fresh copies. As long as the Apple IDs match up you can do this endlessly.

Most are not, unfortunately. Indeed, it is a convenient way but it won't work in this case.

 

[NoBoMac]

if I backup everything on Time Machine (on Catalina), then erase the MacBook and reinstall El Capitan, will I be able to restore all the Apps (and hopefully their parameters [I think of internet history and bookmarks, for instance]) and personal files (downloads, documents, desktop, etc) using Migration Assistant.

In addition to previously mentioned issues with going from a newer version of TM to an older OS, this might cause more problems.

First, some of your programs might be setting up config files, settings, etc. in the /Library folders and need to come over, which will be Catalina and most likely incompatible with El Cap.

If you sign into your account, the files in your Library folder might be Catalina-ed. And will not be compatible with El Cap.

And are some of your programs 32-bit? If so, they are no longer on the Catalina install.

A TM backup should have been done on El Cap before upgrading, at which point you would have had a restore point to fall back to. Backup now is too late.

 

[Fishrrman]

OP wrote:
"if I backup everything on Time Machine (on Catalina), then erase the MacBook and reinstall El Capitan, will I be able to restore all the Apps (and hopefully their parameters [I think of internet history and bookmarks, for instance]) and personal files (downloads, documents, desktop, etc) using Migration Assistant."

My guess is:
PROBABLY NOT.

You should understand that migration assistant and setup assistant are "one-way" utilities.
That is, they will migrate from "older to newer", but probably will refuse to migrate "from newer to older".

But... there's another way. Are you willing...?
You will need CarbonCopyCloner.
CCC is free to download and use for 30 days
Doing it this way will cost you nothing.
You'll also need an external drive.

Use CCC to create a BOOTABLE CLONED BACKUP of the Catalina install.
This will preserve your apps and data, etc.
They will be accessible in "plain old finder format" -- just connect the drive and copy over what you need to copy.

Be aware that you must then ENTIRELY ERASE the internal drive -- you CANNOT erase it from the recovery partition.

That means you must either:
- boot to INTERNET recovery
or
- you could boot from the cloned backup and erase the drive that way.

For internet recovery, try this special key combo first:
shift option command R
This may take you to a utilities "load up" that will let you install the oldest version of the OS that shipped with your MacBook.
For a mid-2015, I'm guessing that will be El Cap.

If that doesn't work, you could get dumped into a version of internet recovery that will want to re-install Catalina. You want to decline that.
In that case, you'll have to try to create a bootable USB flashdrive installer and see if that works.