I run the script under rosetta on an M1 with python3 by using: arch -x86_64 scripts/SMJobBlessUtil-python3.py check path_to_bundle It seems to work

If you are using an Apple Silicon Mac, have you tried running the script under Rosetta2?

I ran into a similar problem a few months back. The solution was to upgrade SMJobBlessUtil.py to python3. The issue was covered in https://developer.apple.com/forums/thread/699310 The conversion seems to work but I have only run it with my own use cases and not done any rigorous testing.

I have a suspicion that this problem is related to the libresolv security patches applied in https://support.apple.com/en-us/HT213257 and https://support.apple.com/en-us/HT213256 to macOS. Presumably this same libresolv security fix was also applied to iOS.

I have a suspicion that this problem is related to the libresolv security patches applied in https://support.apple.com/en-us/HT213257 and https://support.apple.com/en-us/HT213256.

@mikeyh Thank you so much for this. I have just tried your patched code and it is working in my build process. I'll refrain from marking your solution as accepted for now, just in case there are more comments/improvements from others, but it seems to be working fine.

I am pretty sure the limiting factor here is not the RAM allocated to the copy/move process but instead the speed of your devices. What is the transfer rate of your source device? What is the transfer rate of the target? Are you using USB? Are these SSD devices? Is it a network connecton? All of these have for more impact than the amount of memry allocated to the process.

By default CCC will only do a clone of the Big Sur data volume. I suspect that you have not made a bootable backup, i.e. also including the system volume. The CCC web-site has details on how to make a bootable backup with CCC running on Big Sur.