Restoring original Operating System?

[Apple_Glen_UK]

Despite the fact I have a 13” MacBook Pro (2015) I have just purchased a 15” Mid-2015 MBP with 16GB RAM and 256GB SSD. It is described as being in mint condition, looks to be in mint condition from the photos I have seen and it is still boxed. I got it for a decent price so may keep it and sell my 13” or, perhaps, I’ll give the 13” to my wife. I picked it up for £625 which – when I compare it with other similar models – looks to be a very good price. It has a low-ish battery cycle count (119) and has been checked and is not affected by the battery issues some of these models have had. My question is this; it has been upgraded to Catalina which I don’t particularly want it to be on. I could live with it, but I would prefer to be on Mojave. If I restore all factory settings etc, will that restore the machine to its original OS (probably El Capitan, possibly Yosemite)?

 

[Fishrrman]

The following procedure should install the original version of software that shipped on that MBP:

BEFORE DOING THIS, MAKE SURE YOUR PERSONAL DATA IS BACKED UP SOMEWHERE!!!!!

1. Boot to a special version of internet recovery mode:
shift-OPTION-command-R
(you will need your wifi password)

2. Give some time for the internet utilities to load (spinning globe)

3. When you get to the utilities menu, open Disk Utility

4. IF there is a "view" menu, choose "show all devices"
(if you DON'T see this menu, don't worry about it)

5. Select the TOPMOST line on the left that represents the physical drive inside the Macbook, and ERASE it to "Mac OS extended with journaling enabled", GUID partition format

6. Once the erase is done, install the OS.

That should "get you back to the beginning". You can update from there to wherever you want to go.

 

[Apple_Glen_UK]

The following procedure should install the original version of software that shipped on that MBP:

BEFORE DOING THIS, MAKE SURE YOUR PERSONAL DATA IS BACKED UP SOMEWHERE!!!!!

1. Boot to a special version of internet recovery mode:
shift-OPTION-command-R
(you will need your wifi password)

2. Give some time for the internet utilities to load (spinning globe)

3. When you get to the utilities menu, open Disk Utility

4. IF there is a "view" menu, choose "show all devices"
(if you DON'T see this menu, don't worry about it)

5. Select the TOPMOST line on the left that represents the physical drive inside the Macbook, and ERASE it to "Mac OS extended with journaling enabled", GUID partition format

6. Once the erase is done, install the OS.

That should "get you back to the beginning". You can update from there to wherever you want to go.

I shall give it a try. Thank you!

 

[Brian Y]

You can install any intermediate version you like if you create a USB installer. Just download the required version from the App Store (still possible), and use the "createinstallmedia" command to create a bootable USB.

 

[Analias]

I shall give it a try. Thank you!

You'll be better off formatting apfs not hfs+. You won't get updates on a hfs+ formatted Mojave install. Plus apfs is faster.

 

[Nermal]

If you're restoring the original OS on a 2015 machine then you'll need to use HFS+. If you subsequently update to Mojave then it'll automatically convert back to APFS.

 

[Analias]

If you're restoring the original OS on a 2015 machine then you'll need to use HFS+. If you subsequently update to Mojave then it'll automatically convert back to APFS.

You only need to use hfs+ if the boot rom has not been updated yet. As it is currently running Catalina, which can only be installed to apfs, then the boot rom has already been updated and it is fine to go straight to apfs.

 

[Nermal]

Are you sure? Admittedly I haven't tested it, but I'd imagine that the original OS 10.10 installer won't even be able to "see" an APFS volume to install to in the first place.

 

[Analias]

Are you sure? Admittedly I haven't tested it, but I'd imagine that the original OS 10.10 installer won't even be able to "see" an APFS volume to install to in the first place.

Yes I'm sure. Booting from apfs was enabled in the high sierra update where a new boot rom firmware is installed. The boot rom has definitely been updated as the mac in question is currently running Catalina. Catalina cannot be installed on anything other then apfs. Mojave can be installed on either, however automatic updates will not work if it's not installed on an apfs volume.

10.10 probably won't see an apfs volume, but this mac is running 10.15 so the point is moot.

 

[Brian Y]

Are you sure? Admittedly I haven't tested it, but I'd imagine that the original OS 10.10 installer won't even be able to "see" an APFS volume to install to in the first place.

It won't, you'd have to erase the disk before installing.

 

[DeltaMac]

If you choose to go back to the original OS, which might be Yosemite, then you do have to erase, and format to HFS+.
Even if the "new" MBPro had Catalina installed, you can still go back to Yosemite. The Yosemite installer won't see an APFS volume at all, so the boot drive has to be re-formatted to HFS+
And, if you install your choice of Mojave, that installer will convert the HFS+ boot volume to APFS automatically, so no real need to choose APFS as the new format, the installer does that for you. (It won't somehow end up as HFS+, not possible with a standard Mojave install. You can restore a Mojave system to an HFS+ volume, if you have a special need, but there's not many valid reasons for doing that)