Need help erasing APFS formatted disk

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Level 1

9 points

Need help erasing APFS formatted disk

Hi all,

After a botched security update from Apple and subsequent failed attempt at a Time Machine restore, my Macbook Pro which was running High Sierra 10.13.6 now fails to boot (I get the prohibited symbol at start-up).

At this point I can only enter Internet Recovery mode. From here I've made the following attempts to recover my system.

Re-attempted to restore from Time Machine. This fails with an error that "Macintosh HD" failed to erase.
Running First Aid in Disk Utility on "Macintosh HD". Fails with error code 8.
Attempted to erase "Macintosh HD" using Disk Utility. Fails for both APFS or Extended Journaled formats.
Attempted to re-install Mac OS Sierra. Fails with error stating install cannot be done since a newer version of the OS was detected.

Fortunately all my data is backed up so at this point, so it would appear that my only option is to attempt to erase the physical SSD drive (APPLE SSD..). Disk Utility only gives me the option to erase the SSD using Extended Journaled format. I haven't attempted this yet as I'm not sure if doing this will erase the APFS container (AppleAPFSMedia) and associated volumes and leave me with a disk I can attempt to re-install the OS onto.

This is where I am right now with Disk Utility

Any suggestions on what is the right way to erase my APFS formatted disk so that I can re-install the OS would be greatly appreciated.

MacBook Pro TouchBar and Touch ID, macOS High Sierra (10.13.6)

Posted on Nov 9, 2018 6:36 AM

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Answer 1

Top-ranking reply

John Lockwood

Level 6

13,697 points

Nov 9, 2018 7:42 AM in response to sfmbp

Not really your fault but it looks like you are erasing the APFS volume inside the 'Container'. This will not do what you want as this leaves the structure of the entire disk in the arrangement setup for APFS.

What you need instead to do is select the top parent which in your case is the APPLE SSD SMD5… entry and format that as Extended Journaled. This will remove the entire container and the APFS volume within it and setup a standard volume aka HFS+.

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Answer 2

sfmbp Author

Level 1

9 points

Nov 10, 2018 7:31 AM in response to John Lockwood

I finally got this sorted out. Just for the record here is what I had to do.

Erase and format AppleAPFSMedia (chose Extended Journaled, and name Macintosh HD). This successfully reformats the drive. Note, it is was not possible to erase / format the physical disk APPLE SSD.
Re-install OS Sierra from the recovery menu. Note, attempting to directly restore the Time Machine backup to the empty formatted drive does not work (the restore operation succeeds but the OS will not boot).
After re-installing OS Sierra, I was able to reboot into local recovery mode (command-R), no longer Internet Recovery.
From local recovery mode, chose restore from time machine backup and restore to Macintosh HD.
The restore completed successfully and then the system successfully booted back up and everything was restored.

Thanks all for your help.

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Answer 3

Nov 9, 2018 8:02 AM in response to sfmbp

sfmbp wrote:

Thank you for the prompt response John. Your recommendation is as I suspected, I just wasn't sure if it was the right thing to do. 🙂

So after formatting APPLE SSD SMD5... for Extended Journaled, should I be able to re-install Sierra or attempt to restore my last Time Machine back-up (based on High Sierra)?

Much thanks for your assistance.

Yes to both, once correctly formatted you will be able to reinstall Sierra or restore a pre-Mojave version from your Time Machine backup.

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Answer 4

Nov 9, 2018 8:15 AM in response to QuietMacFan

i'm unsure if you attempted to restore backup, "re-install", or "install factory default" (completely start fresh)

you might try this to get around your "OS is newer" issue (your external drive may or may not be prepared to boot using the older OS, i don't know)

How to select a different startup disk - Apple Support

i'm unsure why you think SSD is the problem, all your actions were against HD

but i do know you can "skip SSD" (ignore it or reformat it) and fix the "damage" you did later after an OS is installed (there are Terminal commands to link it back to HD, using a comandline disk partitioner)

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Answer 5

sfmbp Author

Level 1

9 points

Nov 9, 2018 7:42 AM in response to John Lockwood

Thank you for the prompt response John. Your recommendation is as I suspected, I just wasn't sure if it was the right thing to do. 🙂

So after formatting APPLE SSD SMD5... for Extended Journaled, should I be able to re-install Sierra or attempt to restore my last Time Machine back-up (based on High Sierra)?

Much thanks for your assistance.

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Answer 6

sfmbp Author

Level 1

9 points

Nov 9, 2018 8:18 AM in response to QuietMacFan

Reformatting would be enough for me, my question was really about what it the right thing to format given that I'm in a state where formatting the boot volume (Macintosh HD) as I would typically do is failing for me. I was unsure if re-formatting the physical SSD drive was the right choice to make to get my system back to a state where I can re-install the OS or restore from Time Machine.

Thank you for the install tip regarding using a secondary drive.

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Answer 7

Nov 9, 2018 8:23 AM in response to QuietMacFan

Attempted to re-install Mac OS Sierra. Fails with error stating install cannot be done since a newer version of the OS was detected.

i seem to remember seeing that message once. i did a "factory restore". i'm unsure if factory restore "just works" or if i selected a time machine backup as a startup disk. but i think there's a way around it if your intent is to "factory restore" the mac

if not, i'd call apple. they may direct you to take it to a local store for free or something or direct you to the location of a startup disk you need.

you can run Terminal and it may have disk partition and disk format and other utilities. i'm unsure what is available in Recovery Mode exactly.

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Answer 8

Nov 9, 2018 8:02 AM in response to sfmbp

,

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Need help erasing APFS formatted disk

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