Resolved Need help erasing APFS formatted disk

sfmbp

macrumors newbie
Original poster
Nov 7, 2018
3
0
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 Fails with error stating install cannot be done since a newer version of the OS was detected.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.

Link to my view of Disk Utility
https://imgur.com/a/M78LzIC

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.

Thanks,
Steve
 
Last edited:

sfmbp

macrumors newbie
Original poster
Nov 7, 2018
3
0
Ahh and after reading a few other threads, I now know that it was the Safari and security update that Apple released in the past week that got me into this mess. I see a few other posters reporting the same update error failure that I encountered which I attempted to fix with a Time Machine restore.
 

Macshroomer

macrumors 65816
Dec 6, 2009
1,126
525
Ahh and after reading a few other threads, I now know that it was the Safari and security update that Apple released in the past week that got me into this mess. I see a few other posters reporting the same update error failure that I encountered which I attempted to fix with a Time Machine restore.
I’m in the same boat, updating to Mohave to see if I can emerge currently.
 

HenryAZ

macrumors 6502a
Jan 9, 2010
605
97
South Congress AZ
Use Disk Utility in Recovery, select the main disk and Partition. Partition the whole thing and you will be offered choices of formatting options. Select HFS+ and reformat it. This gets rid of all the APFS partitions and returns the disk to a plain HFS+ disk, ripe for a re-install.
 
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sfmbp

macrumors newbie
Original poster
Nov 7, 2018
3
0
Use Disk Utility in Recovery, select the main disk and Partition. Partition the whole thing and you will be offered choices of formatting options. Select HFS+ and reformat it. This gets rid of all the APFS partitions and returns the disk to a plain HFS+ disk, ripe for a re-install.
Thank you for the advice Henry. I was able to recover my system. Here's the specific steps that ended up working for me.
  • Erase and format AppleAPFSMedia (chose Extended Journaled, and name Macintosh HD). This successfully reformatted 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.
Note this ended up restoring to a system using Extended Journaled file system. To get back to an APFS file system it was necessary to boot back into recovery mode, launch Disk Utility, select Macintosh HD, unmount it and then perform convert to APFS from the edit menu options.