Can I For Sure Downgrade Back To High Sierra From Mojave?

[Hoff]

I have 2015 MBP with High Sierra.
I have no desire to upgrade to Mojave except to quickly back up my iPhone 11, and then reformat it and restore from that back up.

And High Sierra won't recognize my iPhone 11.

I've heard you can reformat the MBP from Mojave back to the OS that it shipped with.
But can you tell me for sure this will work and I won't be stuck with Mojave on my 2015 machine?

Would I need to create an installer media while I still have High Sierra?
Or what would I need to do?

 

[Porco]

iPhone 11 is supposed to be supported as far back as El Capitan. Have you tried using a different lightning cable?

 

[4sallypat]

Depending on which OS originally came with your MBP, you have 3 choices for internet recovery without having to create installer drive:

https://support.apple.com/en-us/HT204904

Command (⌘)-R
Reinstall the latest macOS that was installed on your Mac (recommended).
Option-⌘-R
Upgrade to the latest macOS that is compatible with your Mac.
Shift-Option-⌘-R
Reinstall the macOS that came with your Mac, or the closest version still available.

 

[||\||]

If you clone the boot drive, you can go forward or backward to any operating system that has been previously installed.

 

[PBG4 Dude]

You can install Mojave to an external drive, then run it from there and leave your internal drive on High Sierra.

 

[Hoff]

Depending on which OS originally came with your MBP, you have 3 choices for internet recovery without having to create installer drive:

https://support.apple.com/en-us/HT204904

Command (⌘)-R
Reinstall the latest macOS that was installed on your Mac (recommended).
Option-⌘-R
Upgrade to the latest macOS that is compatible with your Mac.
Shift-Option-⌘-R
Reinstall the macOS that came with your Mac, or the closest version still available.

Cool. Thanks. I used that Shift-Option-⌘-R to reinstall High Sierra once already.
Just for verification, has anyone tried this in a downgrade scenario and it worked ok??

 

[Crash0veride]

Cool. Thanks. I used that Shift-Option-⌘-R to reinstall High Sierra once already.
Just for verification, has anyone tried this in a downgrade scenario and it worked ok??

As far as I am aware you can not use the "reinstall" method to downgrade and keep your current filesystem (apps, documents, etc) intact. Wiping the system, installing the OS fresh, and restoring from a time machine backup created before you upgraded is required. Someone else feel free to correct me If I'm wrong.

I downgraded from Mojave to HS when Mojave was initially launched due to Adobe problems. That was my experience.

You can also do one of the other methods above to make a clone of your HS drive for backup purposes.

 

[yukari]

Why not just use Time Machine or some other cloning program? Why go through all the hassle?

 

[honestone33]

Why not just use Time Machine or some other cloning program? Why go through all the hassle?

Exactly! SuperDuper! will do the job just fine:

SuperDuper!

 

[Hoff]

iPhone 11 is supposed to be supported as far back as El Capitan. Have you tried using a different lightning cable?

BRILLIANT!
Thanks to your suggestion I was able to back up the iPhone 11 on High Sierra.

I had to update iTunes first to 12.8 with the iPhone plugged in. Then it said something like "You need to install an update to connect your iPhone." I always thought it meant update to Mojave. But it just meant something in iTunes.

Anyway it worked. So glad I don't have to update to Mojave! Thank you 😁

 

[Hoff]

If you clone the boot drive, you can go forward or backward to any operating system that has been previously installed.

Thanks. I'd like to do that to be safe. Two questions. 1) is that something I should do mainly right after a fresh install of High Sierra? and 2) is this link the way you'd suggest doing it, from Disk Utility?

How to Make a Bootable Clone of Your Mac's Hard Drive

There are a lot of reasons for wanting to boot from an external drive.

www.howtogeek.com

 

[Hoff]

As far as I am aware you can not use the "reinstall" method to downgrade and keep your current filesystem (apps, documents, etc) intact. Wiping the system, installing the OS fresh, and restoring from a time machine backup created before you upgraded is required. Someone else feel free to correct me If I'm wrong.

I've got all my files backed up. Would it work if I wiped it?

Or how do you do a "fresh" install of the previous operating system? Do you have to make a bootable clone? I wish my Mac just came with install media for the original OS. How do I create a clean install media of my High Sierra?

I'm not using TimeMachine or any cloning software currently.

 

[Wowfunhappy]

Have you considered downloading a trial of VMWare Fusion? You can set up a copy of Mojave within a little window and delete it when you're done! Much easier!

Virtualbox can theoretically do it too (free forever), but it can be a bit difficult to get Mac guests working (and they don't work well), whereas with VMWare you just follow the prompts.

Edit: Ah, nvm, you already got the iPhone backed up! Good for you!

 

[Crash0veride]

I've got all my files backed up. Would it work if I wiped it?

Or how do you do a "fresh" install of the previous operating system? Do you have to make a bootable clone? I wish my Mac just came with install media for the original OS. How do I create a clean install media of my High Sierra?

I'm not using TimeMachine or any cloning software currently.

Having your files backed, up won't make your machine just like it was before you upgraded, but you can downgrade. The beauty of time machine is it would be exactly as it was when the backup was made, including app settings and configuration files. No manually putting files back in the correct places. You can certainly downgrade without restoring your machine through time machine though.

You don't need to make a clone, just another way, as people mentioned to keep your system intact and test an upgrade, but is unnecessary for a clean wipe. Basically the only difference between a "fresh" install and re-installing is you erase your current OS before installing. The link below has some instructions for a clean install. If you make a time machine backup, after erasing the disk, in step "9" you could restore from your Time Machine backup created prior to upgrading instead. You could also do that after re-installing though.

How to Clean Install MacOS Mojave

Performing a clean install of MacOS Mojave may be desirable to some Mac users. A clean install means erasing all data on a hard drive, and then installing a fresh new installation of MacOS Mojave t…

osxdaily.com

 

[Fishrrman]

OP:

There's an EASY WAY to "get back, get back, get back to where you once belonged" if you want to try Mojave.

That way is:
Download CarbonCopyCloner -- it's FREE to download and use for 30 days.

Download CCC - Bombich Software

www.bombich.com

Then...
Use CCC to create a BOOTABLE CLONED BACKUP of your current High Sierra install.

Now, set the cloned backup aside in a safe place.

Next, upgrade to Mojave.
If you like it, fine. Keep the High Sierra cloned backup for a month or two, just to be sure.
If you DON'T LIKE Mojave, now it's EASY to go back to High Sierra by doing this:
1. Boot from the cloned High Sierra backup
2. ERASE the internal drive using disk utility
3. RE-Clone the cloned backup BACK TO the internal drive.
It will "look like you never left".

There are other ways to "get back", but the AREN'T going to be "easy"...