Downgrading from Catalina to High Sierra what am I doing wrong?

[Waikiki]

Hi everyone,

I wonder if anyone could tell me where I am going wrong in my attempt to downgrade from OS 10.15 (Catalina) to 10.13 (High Sierra).

Computer: Desktop iMac, late 2012, 27-inch.

Objective: To use Photoshop CS6 with a graphics tablet (Adobe CS6 will not work with Catalina).


What I have tried:

Creating a bootable installer on a USB flash drive.
I downloaded the installer for High Sierra, typed in the appropriate command into Terminal (which I am not familiar with at all, just following steps provided elsewhere) and the procedure was successful.
The USB is a Toshiba, 16GB. It is not especially fast but it was the only one I had with the required 14GB of space.

Next I tried to install High Sierra via the USB. Booted up while holding Option. Released it when the screen showed bootable volumes; selected my USB, selected install High Sierra. The installation process did not complete, giving the error message "com.apple.osinstall error -3"
I tried this three times.

Solutions that I tried after this:

1. Booted while holding Command + Shift + Option + R. The computer started the process to install OS 10.8 (Mountain Lion) but it did not show any clickable Hard Drive icon to install it on.

2. I read that it could work if you revert from APFS file system to the older HFS+ one (again, not something I'm familiar with). There is a command to enter in Terminal, but I had no idea how to use Terminal when using a boot installer on USB.


I'm out of ideas so any suggestions you could give me would be most useful. Also if I haven't clarified anything, please ask.
Thanks very much for reading.

 

[TonyAguila]

Hi everyone,

I wonder if anyone could tell me where I am going wrong in my attempt to downgrade from OS 10.15 (Catalina) to 10.13 (High Sierra).

Computer: Desktop iMac, late 2012, 27-inch.

Objective: To use Photoshop CS6 with a graphics tablet (Adobe CS6 will not work with Catalina).


What I have tried:

Creating a bootable installer on a USB flash drive.
I downloaded the installer for High Sierra, typed in the appropriate command into Terminal (which I am not familiar with at all, just following steps provided elsewhere) and the procedure was successful.
The USB is a Toshiba, 16GB. It is not especially fast but it was the only one I had with the required 14GB of space.

Next I tried to install High Sierra via the USB. Booted up while holding Option. Released it when the screen showed bootable volumes; selected my USB, selected install High Sierra. The installation process did not complete, giving the error message "com.apple.osinstall error -3"
I tried this three times.

Solutions that I tried after this:

1. Booted while holding Command + Shift + Option + R. The computer started the process to install OS 10.8 (Mountain Lion) but it did not show any clickable Hard Drive icon to install it on.

2. I read that it could work if you revert from APFS file system to the older HFS+ one (again, not something I'm familiar with). There is a command to enter in Terminal, but I had no idea how to use Terminal when using a boot installer on USB.


I'm out of ideas so any suggestions you could give me would be most useful. Also if I haven't clarified anything, please ask.
Thanks very much for reading.

macOS Catalina requires the two-partition scheme, system+data on APFS, so the High Sierra installer will not be able to write over the protected system volume. In short, you will have to erase the Catalina installation (both system AND data) and delete the APFS container, before reformatting the drive to HFS+. This means you will lose all that information, so you should have a Time Machine (or other) backup of the present setup to do a migration from.

You are fortunate to have a system installer thumb drive. If that fails, I have found a method of creating an installer (also Terminal-based) that I have found to be the best I have tested so far. Or, at least I have created installers from Mojave all the way to Monterey with it that work. Not sure about High Sierra. My Mac can only run Mojave and later.

 

[Waikiki]

macOS Catalina requires the two-partition scheme, system+data on APFS, so the High Sierra installer will not be able to write over the protected system volume. In short, you will have to erase the Catalina installation (both system AND data) and delete the APFS container, before reformatting the drive to HFS+. This means you will lose all that information, so you should have a Time Machine (or other) backup of the present setup to do a migration from.

You are fortunate to have a system installer thumb drive. If that fails, I have found a method of creating an installer (also Terminal-based) that I have found to be the best I have tested so far. Or, at least I have created installers from Mojave all the way to Monterey with it that work. Not sure about High Sierra. My Mac can only run Mojave and later.

Thanks very much for your reply.
Would you mind explaining briefly how I can erase the Catalina installation, and reformat the drive to HFS+? I'd really appreciate it.

 

[TonyAguila]

Thanks very much for your reply.
Would you mind explaining briefly how I can erase the Catalina installation, and reformat the drive to HFS+? I'd really appreciate it.

Sorry to not go into detail. Restart into Recovery (hold down ⌘-R). Once in Recovery, if I recall right, you will be asked to log in. The main Recovery window opens, select Disk Utility. In the main Disk Utility window, click on the View pull down and select Show All Devices.

On the side bar, the drive(s) will display the drive itself, and below it the container(s) and volumes. Select the drive and in the main window, click on Erase. If this is your internal drive you may want to name it Macintosh HD. For format, choose Mac OS Extended (Journaled). You don’t want APFS since it will probably be foreign to High Sierra.

Reminder: Before erasing, make sure you are confident in your High Sierra installer USB drive, and Time Machine backup. You will lose all the data on your drive and will need to migrate your previous information from backup. I’ve done this procedure a good number of times and am comfortable with it, but it can still be scary.

Once Disk Utility is finished, restart with your flash drive installer and proceed with the installation. Good luck!

 

[Waikiki]

Thanks very much Tony – no apologies required! I really appreciate your detailed instructions. I have never used Time Machine before and have been reading up about it so I can make a backup. Thanks again!

 

[TonyAguila]

Thanks very much Tony – no apologies required! I really appreciate your detailed instructions. I have never used Time Machine before and have been reading up about it so I can make a backup. Thanks again!

Cheers! Time Machine setup is really easy. In your case, use a drive that’s at least twice the capacity of your main drive. Erase and format it HFS+ (I would choose APFS if using in a Big Sur or Monterey environment). Do not encrypt right away, just erase and give it a name. While attached to the Mac, open System Preferences -> Time Machine. Depending on your setup, you may have to click the pad lock to do the setup.

Click on “Add or Remove Backup Disk…” and select the target drive. I suggest turning encryption ON to secure your data. Then go ahead and perform your first TM backup.

I always set up two Time Machine drives for redundancy.

 

[Waikiki]

Cheers! Time Machine setup is really easy. In your case, use a drive that’s at least twice the capacity of your main drive. Erase and format it HFS+ (I would choose APFS if using in a Big Sur or Monterey environment). Do not encrypt right away, just erase and give it a name. While attached to the Mac, open System Preferences -> Time Machine. Depending on your setup, you may have to click the pad lock to do the setup.

Click on “Add or Remove Backup Disk…” and select the target drive. I suggest turning encryption ON to secure your data. Then go ahead and perform your first TM backup.

I always set up two Time Machine drives for redundancy.

That's great, thanks again! I really should have used Time Machine before but all this time I've just been manually copying files onto portable hard drives, but this is all really useful to know. I'll get started on this later today.

 

[rainharvester]

I have the same -3 error. Do i need a thumb drive or magic time machine if i WANT to clear out the old info?

Can i erase the ssd and continue? Or will it get stuck because it will erase the program that reinstalls high Sierra? (I'm also on Catalina 10.15.3).

 

[rainharvester]

I have the same -3 error. Do i need a thumb drive or magic time machine if i WANT to clear out the old info?

Can i erase the ssd and continue? Or will it get stuck because it will erase the program that reinstalls high Sierra? (I'm also on Catalina 10.15.3).

Waikiki,
I was wondering if,after erasing the ssd, i could reboot with command control r to install from internet? Doing this now, gives me the -3 error.

Or would i still need a thumb drive?

If i erase, i won't be able to get to disk utilities again, correct?

 

[TonyAguila]

Waikiki,
I was wondering if,after erasing the ssd, i could reboot with command control r to install from internet? Doing this now, gives me the -3 error.

Or would i still need a thumb drive?

If i erase, i won't be able to get to disk utilities again, correct?

Internet Recovery (cmd-opt-R) gets problematic, try Recovery (cmd-R) first. Once you’re in Recovery, if you wish to reformat the SSD, select Disk Utility and do the erase from there. If you select the device (SSD) instead of the volumes, you should be able to erase the Catalina volumes. You can then erase the drive as HFS+ or APFS, your choice. From there, Recovery will offer the newest version of macOS for installation. You have no other choice. If you need an older version of macOS, you will need an installer disk with the specific macOS version you want.

Disk Utilities is loaded online, so just make sure you have an internet connection before starting. Again, you don’t need Internet Recovery to do this.

 

[rainharvester]

Thank you.
If the latest OS is the only option offered, why is internet reinstall attempting to install high Sierra when Catalina 10.15.3 is already on my 2011 imac?

 

[Waikiki]

Waikiki,
I was wondering if,after erasing the ssd, i could reboot with command control r to install from internet? Doing this now, gives me the -3 error.

Or would i still need a thumb drive?

If i erase, i won't be able to get to disk utilities again, correct?

Hi Rainharvester,

Sorry for my delayed reply, but Tony has kindly given you a much more detailed explanation than I could. I hope what he has suggested works for you. You should still be able to use Disk Utilities.

 

[TonyAguila]

Thank you.
If the latest OS is the only option offered, why is internet reinstall attempting to install high Sierra when Catalina 10.15.3 is already on my 2011 imac?

Someone must have done some tinkering with your iMac to allow for installing macOS 10.15. The last 2011 iMac was rated to max out at macOS 10.13.6. Perhaps this was the cause of the problems you encountered.

 

[Harry Trent]

What Tony said. Someone used a hacked installer in order to install Catalina on your 2011 iMac. Catalina is not officially supported on that year iMac but people have developed hacked work arounds.

 

[TonyAguila]

What Tony said. Someone used a hacked installer in order to install Catalina on your 2011 iMac. Catalina is not officially supported on that year iMac but people have developed hacked work arounds.

Correct. It’s not uncommon. More often than not, downgrading can become a challenge. Software updates oftentimes will also update the Mac’s firmware, which can then make it harder, if not impossible, to downgrade the system.

Every time I update macOS, I make a point of noting the Mac’s firmware version, just so I know if an update happened with the update/upgrade. I know of no method to revert the firmware to the previous version. It’s probably next to impossible without a hardware fix.

To get the firmware data, go to About This Mac and click on System Report…