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Downgrading from Catalina to older os.

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How long does a time machine backup take to restore to a previous os? I'd recently upgraded to Catalina and then I'd decided that I wanted to restore to an older os, from the recovery window at boot. But the time machine restoration has taken over 9 hours and counting. Is this normal? Or have I done something wrong?
 
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I'm not sure that is possible to do. The issue is that Catalina split the drive into two Volumes, one named MacintoshHD and the other MacintoshHD Data. I don't think TM knows how to undo that split. To recover from Catalina back to Mojave, I think it's up to you to boot into recovery, use Disk Utility to reformat the drive and create just one volume on it again, and then let TM put the system back. It may even be faster to reinstall Mojave at that point and then do a restore of you files when it boots and offers Migration Assistant to bring in your data.

Maybe somebody who has done that can chime in here and correct me or verify what I said?
 
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Catalina would have split the drive into 2 volumes, and this can't be resolved with disk utility.

You have to use terminal to create a single volume before installing Mojave as follows.

Launch the Terminal app, type the following command at the prompt to locate the Physical Store identifier of the APFS partition, and press Return:

diskutil list

When ready to delete the partition, type the following command:

diskutil apfs deleteContainer /dev/Substitute the Physical Store identifier of the APFS partition

You can then install Mojave. I have had to do this quite a few times now for customers who regretted upgrading to Catalina
 
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Catalina would have split the drive into 2 volumes, and this can't be resolved with disk utility.
Really? If you boot from an external drive, invoke Disk Utility, Show the entire drive and erase it that won't resolve the problem? That is stunning, if true. And if it is, it's surprising that diskutil can do it.

You can't change it if you are booted from the drive, of course, but if you boot from something else, it's just a drive and you should be able to do whatever you want.
 

Slydude

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@Jake I think you're right. IIRC that's what I did recently to correct some issues I created.
 
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I know it can be done because I did it when I erased my Catalina upgrade install, and did my Catalina clean install.


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Restoring the same macOS for a clean install is not the same as restoring a previous macOS especially when in has a different volume structure. Creating a bootable Mojave installer, erasing and reformatting and partitioning the HD, installing Mojave and restoring your data from your backup is the way I would go about it but there always more than one way to "skin a cat".


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Thanks to everyone for their helpful comments and advice. I have now, at last, restored my Macbook to the older macOS (High Sierra, which I wanted), though the Macbook had to be totally erased and the downgrade took a few hours. :D
 
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Physical Store Identifier? Which one of these is that?

#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *251.0 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk1 250.8 GB disk0s2
 
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@rexanders, what are you talking about? If you are trying to use the command line in terminal as suggested by techiesteve in post #4 but don't know the answer to your question, it would appear that you don't have enough knowledge about how terminal commands work to be safe using his suggestion. You can do real harm to your system if you get it wrong. Just don't do it.

What are you trying to accomplish? There are less risky ways to do what techiesteve suggested. So tell us what it is you are attempting and we can coach you through it.
 
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Thanks Jake. You're right, I"m not a massive Terminal user but I thought my question seemed straightforward. I want to revert to Mojave but the bootable Mojave installer I carefully created either hangs or or I get the report that the system is too old for Catalina. Obviously the problem is with the two volume split as described in #4.

Here Steve says: "When ready to delete the partition, type the following command:

diskutil apfs deleteContainer /dev/Substitute the Physical Store identifier of the APFS partition"

So the diskutil list command brings up three identifiers, I simply want to know to which one of the three is #4 is alluding, disk0, disk0s1 or disk0s2?
 
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I would not say the problem is with the split. The split would not produce what you say you are seeing at all. Have you backed up your data? If so, then here is what I would suggest. (If you haven't backed up, do so before doing anything. The terminal command will erase EVERYTHING on the drive. Everything!

Remake a bootable installer. Something is wrong with the one you have, it should not even say anything about Catalina if it is a Mojave installer (Mojave doesn't know about Catalina). Boot from the installer. If it is a good installer, it should not hang or get that report. Once booted, you should have an option to use Disk Utility to format the internal drive. Use that to erase/partition the hard drive and create the one partition or Volume as APFS calls it. Then install Mojave from the installer and restore from your back. No need for Terminal at all.

The challenge with just answering your question is that techiesteve referred to "partition" when APFS changed the structure and terminology and no longer uses partition. The drive is now a Container and contains Volumes within the Container. The command he has shown is used to delete the entire container, leaving the drive empty (including empty of all your data). But you can do that from a good installer USB drive using Disk Utility and not worry about the complexity of a terminal command that you don't understand completely. Take the safer route.
 
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Thanks Jake. I'll go back to square one and do as you suggest. However, I already have three bootable installers (two from the last rendition of Mojave and one from a couple of versions earlier) and none of them seem to work.
 
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Thanks to everyone for their helpful comments and advice. I have now, at last, restored my Macbook to the older macOS (High Sierra, which I wanted), though the Macbook had to be totally erased and the downgrade took a few hours. :D
I made the mistake of upgrading to Catalina. Make that huge mistake. Not only does it mess with the HD on my MacBook Pro, but it messed with every Pages file in my system and change the file structure to Apple's latest file structure to suit SSDs which I have been using for a decade now. I publish a daily web site (mybirdie.ca) for the past 12.5 years now and have files stored for usage in future that number in the hundreds. My backup Mac Mini is on High Sierra and nearly everything I try to use, will not function with Catalina files and vice versa. Catalina also killed so many of the apps I use daily, citing it could not run them, that it left me in big trouble.

Thank goodness I not only use Time Machine but also do a daily clone via Carbon Copy Cloner. I reverted to Mohave by erasing the HD using Disk Utility and replacing the OS, then ridding myself of Catalina, never to upgrade again as the new file structure creates so many issues I simply refuse to deal with it.

Beware Catalina, if you have more than one Mac you use as a backup system. I suspect I will be on Mohave for the next decade.

Apple, always tinkering with stuff that worked fine until they touched it. Never again.
 

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Welcome to our forums.

Apple has been warning users for the past two years that 32 bit apps would no longer be compatible. At the time they first issued the warning it was going to be for Mojave but they relented and decided it would be Catalina instead.

As for APFS, (new Apple file system) it should have no impact on the apps you run or the structure of your hard drives. If you reverted to Mojave, you still maintained the APFS file format regardless of running a SSD or spinner drive. There is a work around for keeping the HFS+ file system with Mojave but it's not something I would recommend.

Glad to hear that you were wise enough to know that backups are invaluable. Carbon Copy Cloner has saved me from disaster numerous times.

I too am sticking with Mojave as I have an app that is 32 bit that I can not do without. However, I keep up with Catalina by booting it from an external SSD. (Samsung T5)
 
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