Could not validate sizes – Operation not permitted. The operation couldn’t be completed. (OSStatus error 1.)

I am following instructions for creating a Bootable drive (generously provided in this answer by a gentleman named David Anderson). I am using a 16GB SD card to try to create a Bootable drive from my MacBook running Catalina.

The instructions could be simplified by doing a Restore using the Disk Utility to the external drive (SD card or flash drive), with BaseSystem.dmg being the restore source.

The problem is that when I try this, I get the following error (also see screenshot)

Could not validate sizes – Operation not permitted. The operation couldn’t be completed. (OSStatus error 1.)

What does this mean? Is there a better way to fix this than the one given in David Anderson's answer. Or, can the asr command be made to work reliably, so the Disk Utility would not have to be used?

Solution 1:

I think the "Operation is not permitted" may be caused by Disk Utility lacking the necessary admin privileges.

sudo /usr/sbin/asr restore --source BaseSystem.dmg --target /Volumes/MyVolume --erase

Should do the trick (terms and conditions apply)

Solution 2:

You can do it easily using ASR command

• You have to scan your downloaded image via following command

  sudo /usr/sbin/asr imagescan --source ~/Downloads/macOSUpdCombo10.15.7.dmg 
  

• After scan you have to run following coammand to restore the image into the USB.

  sudo /usr/sbin/asr restore --source <IMAGE_PATH> --target /Volumes/<VOLUME_NAME> --erase
  

If there is any issue, please share in here.

Solution 3:

Ok, first of all, to be clear, you are doing this from macOS Recovery or while you are booted up on the bootable USB installer right? Also, a 16GB SD card is not enough to hold macOS Catalina. If you are looking to make an SD card that has a ready installation of macOS Catalina, then you can download the Install macOS Catalina app and then use that to install on the SD card (again, the amount of storage isn't enough). https://support.apple.com/guide/mac-help/reinstall-macos-mchlp1599/mac.

If you are experiencing issues with creating a bootable installer, then I think your best option would be to download the Install macOS Catalina app from the App Store and then use the creatinstallmedia command to create the installer. See the link for more https://support.apple.com/en-us/HT201372.