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?
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)