I'm trying to reinstall macOS to seriously messed up MacBook Pro 2018. Apparently, problems started initially when Big Sur update failed. Computer's disk has since been erased and all accounts have been lost. The computer shows question mark folder when it's started.

Here's what I've tried so far:

  1. Started Mac to startup manager (press ⌥ in startup). No disks are showing, only option is internet recovery, which fails.
  2. Started Mac in recovery mode and ran First Aid on the disk, which says that the volume appears to be OK. In addition to internal Apple SSD, there is macOS Base System Disk Image.
  3. Also in recovery mode, I've ran command bless --info and bless --getBoot which both return Can't access "efi-boot-device NVRAM variable.
  4. Reset NVRAM and SMC, which had no effect
  5. Tried to install macOS from bootable drive, which fails because external boot is disallowed in Startup Security Utility. I cannot change the setting because there is no administrator account.
  6. Tried to start into single user mode (⌘-S), to remove /var/db/.AppleSetupDone file in order to run Mac setup again and get new admin account. Logging into single user mode fails, apparently because there is no startup disk (based on this: https://discussions.apple.com/thread/8448671).
  7. Tried to set startup volume in recovery mode terminal by running command bless -mount /Volumes/Macintosh\ HD/ -setBoot which returns the following:
Can't load /Volumes/Machintosh HD/usr/standalone/i386/apfs.efi
Could not load apfs.efi data from /Volumes/Machintosh HD/usr/standalone/i386/apfs.efi

Any ideas what I should do? I'm guessing that the first thing I need is to get startup disk working and create an administrator account. However, that seems to be easier said than done.

  • Can you create a USB installer and try to install macOS from there?
    – X_841
    Jan 14, 2021 at 22:07
  • When booting in single-user mode did you mount the disk before attempting to write to the drive? Jan 14, 2021 at 23:46
  • @X_841, Yes, I have bootable USB installer made (I made it following these instructions: support.apple.com/en-us/HT201372). However, I cannot use it because booting from external media is disallowed. To change that I need an administrator account, which I don't have. To create an administrator account I need to get into single user mode, which I can't get into because the computer does not have a startup disk.
    – Kilipukki
    Jan 15, 2021 at 6:26
  • @pemby the problem is that I cannot get into single user mode at all. When I reboot the computer and press ⌘-S it just shows the question mark folder icon. I believe that this is due to missing startup drive.
    – Kilipukki
    Jan 15, 2021 at 6:30
  • Can you not just install the OS from Recovery? Also, do you not have a backup to restore?
    – benwiggy
    Jan 15, 2021 at 8:08

1 Answer 1


Agree with X_841. It sounds like you need to create a USB installer disk and reformat the hard drive or SSD from there.

  • I have created the USB installer. The problem is that external booting is disallowed in Startup Security Utility. To change that, I need admin account, which I don't have. And to create one, requires access to single user mode, which I cannot acccess because of missing startup disk.
    – Kilipukki
    Jan 15, 2021 at 6:35
  • 1
    This is not a good answer. You just took my comment and added no info, not even how to do a clean install. Also OP has now stated several times this approach doesn’t work.
    – X_841
    Jan 15, 2021 at 7:11

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