Resolved Restoring factory settings went crazy

[Kamigreen]

Hello,
So I’m completely confused by what happened to a usually simple procedure:
I prepared my late 2015 iMac that was running Mojave for a total restore of factory setting. Saved all my files and everything.
Then simply went to disk utility and erase my Macintosh HD. The “only” format option available was APFS (my iMac was delivered running MacOs journaled). So I formatted in APFS and when I rebooted in Recovery Mode and tried to reinstall macOs I got an error.
Went to look at disk utility and I have a crazy amount of partitions, sub folders and virtual disk images and i can’t erase any of it. (Picture included)
I did nothing out of the ordinary, I don’t understand where all this comes from and I can’t fix on my own... anybody’s has suggestion?
Appreciate the help...

 

[CoastalOR]

Hello,
So I’m completely confused by what happened to a usually simple procedure:
I prepared my late 2015 iMac that was running Mojave for a total restore of factory setting. Saved all my files and everything.
Then simply went to disk utility and erase my Macintosh HD. The “only” format option available was APFS (my iMac was delivered running MacOs journaled). So I formatted in APFS and when I rebooted in Recovery Mode and tried to reinstall macOs I got an error.
Went to look at disk utility and I have a crazy amount of partitions, sub folders and virtual disk images and i can’t erase any of it. (Picture included)
I did nothing out of the ordinary, I don’t understand where all this comes from and I can’t fix on my own... anybody’s has suggestion?
Appreciate the help...

Your picture of Disk Utility looks like an older version for an older OS since it does not have the View selection button in the upper left. Older Disk Utilities do not handle APFS properly.

Which factory setting (macOS) are you trying to restore?

I have had the best results for reverting from APFS to HFS+ (MacOs journaled (extended)) is using a High Sierra (Mojave should also work) bootable USB installer to boot up then use the installer Disk Utility to erase to HFS+ GUID (NOTE: make sure you set the Disk Utility View to "Show All Devices" then select the top level of internal drive (model name)). Shutdown. Then boot from a USB installer with the desired older OS (for a 2015 iMac it should be Yosemite or El Capitan), then install the older OS.

You have not indicated the kind of internal drive you have, but I have not tried to convert a fusion drive from APFS to HFS+ and might require some additional steps to re-fuse the drives.

Here are some instructions from Apple on erasing a disk that might have some additional information:
https://support.apple.com/en-us/HT208496

 

[Kamigreen]

Your picture of Disk Utility looks like an older version for an older OS since it does not have the View selection button in the upper left. Older Disk Utilities do not handle APFS properly.

Which factory setting (macOS) are you trying to restore?

I have had the best results for reverting from APFS to HFS+ (MacOs journaled (extended)) is using a High Sierra (Mojave should also work) bootable USB installer to boot up then use the installer Disk Utility to erase to HFS+ GUID (NOTE: make sure you set the Disk Utility View to "Show All Devices" then select the top level of internal drive (model name)). Shutdown. Then boot from a USB installer with the desired older OS (for a 2015 iMac it should be Yosemite or El Capitan), then install the older OS.

You have not indicated the kind of internal drive you have, but I have not tried to convert a fusion drive from APFS to HFS+ and might require some additional steps to re-fuse the drives.

Here are some instructions from Apple on erasing a disk that might have some additional information:
https://support.apple.com/en-us/HT208496

So, I did consult this page before erasing and restoring, and since it says that the system will recognize which format you should favor, I decided to just go with the APFS (which was my only option anyway). I did nothing else than erase and reboot. This is so messed up.

My iMac has a Fusion Drive, and currently the factory setting that I'm offered in the Recovery Mode are Sierra. But I can't install it on Mac HD (I get an error) and I can't restore my Time Machine OR erase the disks to a different format. I can't even run First Aid on any disk...

Should I try to make a Mojave installer on a bootable USB drive formatted in APFS? Would that work? I'm at a loss here... I also don't know how to get rid of the two partitions of the main disk that just appeared out of nowhere

 

[DeltaMac]

I think that your fusion drive is now split.
Try following the steps on this page - https://support.apple.com/en-us/HT207584

You can also try using a bootable Mojave installer, and erase the drive in Disk Utility.

 

[Kamigreen]

I think that your fusion drive is now split.
Try following the steps on this page - https://support.apple.com/en-us/HT207584

You can also try using a bootable Mojave installer, and erase the drive in Disk Utility.

Thank you! I ran the terminal commands and my drive seems to be fixed now!
I'm currently creating a bootable Mojave installer USB and if that fails I'll try restoring Sierra from the Recovery Mode.

Any idea why I'm still getting a disk image in disk utility, as shown in the picture enclosed?

 

[Kamigreen]

I think that your fusion drive is now split.
Try following the steps on this page - https://support.apple.com/en-us/HT207584

You can also try using a bootable Mojave installer, and erase the drive in Disk Utility.

Never mind my previous question. I have successfully installed Mojave through a bootable USB. The external mounted drive has disappeared and the installer reformatted my (non-split) Fusion Drive to APFS again. Everything is in order, nothing is broken, all is clean.
Thanks so much for the help!