Plug in new USB flash drive (WARNING: all contents will be erased) and note the assigned device name in Disk Arbitrator's Disks Window (e.g., disk x).Run Disk Arbitrator and set to 'Block Mounts'.cdr extension that hdiutil automatically appended to new_image.img $ hdiutil convert /path/to/image_created_above.dmg -format UDTO -o new_image.img.
Here is the process I used to backup my DiskWarrior bootable USB flash drive and restore it to a new flash drive: Backup The secret was to convert the image format to raw before writing with dd (attempting to restore even the converted image via Disk Utility returned the same 'Restore Failure' error above). Could not validate source - error 254.īy happy chance, I stumbled onto Max's answer which credited drgeoff's reply, which linked to PureDarwin's Disk images page. The asr workaround did not work either, returning Source volume format on device '/dev/disk3' is not valid for restoring. Could not validate source - Operation not supported' kept appearing in Disk Utility as I tried unsuccessfully to restore a bootable USB flash drive image to a new USB flash drive.
