Downgrade from Monterey to El Capitan

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Level 1

8 points

Downgrade from Monterey to El Capitan

Hi everyone, I'm at my wits end here and need help if anyone can?

I won't explain the catalogue of disasters that led me to upgrade my perfectly stable Mac Pro (late 2013) running macOS 10.11.6 to Monterey 12.6 but suffice to say it was AVID's fault. Long story short, I need to revert to 10.11.6 from 12.6.

I have read several articles about how to do this but there is fundamental information missing in every one of them so far.

First of all I restarted in recovery mode and tried to restore from a time machine backup from 3 days ago.

My backups are on an external drive, formatted in HFS+. The MacPro has a 256Gb SSD formatted in APFS. Can't restore from Backup (crazy, right?)

"The system can't be restored onto this disk because HFS systems can't be restored to space sharing APFS volumes. Reinstall macOS on this disk and then use Migration Assistant to transfer data from your backup instead" (What is the point in a backup system that you can't restore from?)

So, I follow the instructions, go and buy a USB pen drive, download the El Capitan installer and make a bootable drive out of the pen drive.

Restart MacPro from the Pen Drive, holding the Alt button, and get to the Startup Manager window.

If I choose "reinstall system", the MacPro SSD does not appear as an option as to where to install it.

If I choose "Restore from Backup" No destination disks appear at all.

If I choose "Disk Utility" no Macintosh HD or Data appears, only the generic, APFS formatted "APPLE SSD SM0256G Media" drive. If go to erase it, it does not give me the option to format it in APFS.

So it appears that I can't erase my MacPro SSD and format it as APFS.

It appears that I cannot install macOS 10.11.6 on the disk from the "bootable" drive.

It appears that I cannot restore from my backups.

Does anyone know what to do???

Thanks in advance.

Mac Pro, macOS 12.6

Posted on Sep 24, 2022 10:12 AM

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Answer 1

Top-ranking reply

steve626

Level 6

13,005 points

Sep 25, 2022 11:06 AM in response to BA Studios

BA Studios wrote:

Thanks but, I didn't say that. The TM Drive is formatted in macOS Extended (Journaled).

That is not the issue at all.

The issue is that the SSD on the Mac Pro is formatted in APFS and was running El Capitan perfectly before the upgrade. In order to upgrade to Monterey I did not reformat the SSD and did not lose any information in the process so I am assuming that the SSD is in the same state now as it was before the upgrade, bar the new Operating system.

El Capitan only runs under HFS+. The El Capitan operating system cannot even access a drive that is APFS, it will report that the drive is "unrecognizable" and "unreadable" and the only thing it can do with an APFS drive is offer to reformat it to a format it can read (like HFS+). The Mac Pro SSD is APFS now because the drive is converted to APFS from HFS+ when you upgrade from El Capitan to Monterey. Monterey requires APFS; the conversion happens during the upgrade without loss of data.

To return to El Capitan, the drive must be erased/formatted to convert back to HFS+. El Capitan cannot install to an APFS drive, only to HFS+.

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Answer 2

HWTech

Level 9

66,686 points

Sep 24, 2022 06:32 PM in response to BA Studios

You need to select the whole physical SSD within Disk Utility. The physical SSD will be identified something like "Apple SSD...." on the left pane of Disk Utility. Erase the physical SSD as GUID partition and MacOS Extended (Journaled). After erasing the whole SSD, then you should be able to select the "Reinstall macOS" option.

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Answer 3

BA Studios Author

Level 1

8 points

Sep 25, 2022 08:52 AM in response to HWTech

Many thanks for getting your reply, I really appreciate it.

However, from your answer there are still things that I either don't understand or don't make sense to me:

I understand that I need to select the whole physical SSD within Disk Utility. In fact, as I said in my post, "only the generic, APFS formatted "APPLE SSD SM0256G Media" drive" appears.

Now, you suggest erasing the SSD as GUID partition and macOS Extended (Journaled) . However the SSD is currently formated in APFS (as it was before the updeate to Monterey) and it needs to be in APFS for the correct functioning of the Mac Pro. What am I missing? Why won't Disk Utility format it as APFS? If I erase as you suggest in GUID partition & macOS Extended (Journaled) how will this affect the import of everything from my time machine backup which was, after all, backed up from a disk formatted in APFS, after reinstalling the El Capitan system ?

Thanks for your continued assistance.

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Answer 4

Owl-53

Level 10

100,105 points

Sep 25, 2022 09:00 AM in response to BA Studios

If the TM Backup drive is Formatted as APFS / GUID Partition Scheme - you will never be able the use it to Restore to an El Capitan Drive

The earliest version of macOS that will understand APFS maybe High Sierra macOS 10.13 or my learned Colleague above may have seen some OS X 10.12 Sierra drives understand APFS in limited functionality

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Answer 5

BA Studios Author

Level 1

8 points

Sep 25, 2022 09:25 AM in response to Owl-53

Thanks but, I didn't say that. The TM Drive is formatted in macOS Extended (Journaled).

That is not the issue at all.

The issue is that the SSD on the Mac Pro is formatted in APFS and was running El Capitan perfectly before the upgrade. In order to upgrade to Monterey I did not reformat the SSD and did not lose any information in the process so I am assuming that the SSD is in the same state now as it was before the upgrade, bar the new Operating system.

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