Cannot Make Bootable Backup in External Drive After Downgrading BigSur to Catalina

[dogdocla]

I love having a bootable backup. I was using SuperDuper! and Carbon Copy Cloner for this, and all was well until I upgraded to Big Sur.

With Big Sur, it's possible to make a bootable backup, but it requires workarounds and is not simple. So, I downgraded to Catalina.

Then, I tried making bootable backups with SuperDuper! 3.31 and CCC 6.02, but the destination disk does not seem to get blessed, and will not act as a startup disk. The backup disk appears in the Preference Panel box of startup drives, but that does not seem to matter. I tried Command-R at startup, choosing the backup drive to restart, but then I just get the folder with the question mark.

My hardware situation has not changed. I have a trash can MacPro 6,1 with Catalina 10.15.7. My internal SSD is Apple SSD SM1024G. My external drive enclosure is a ThunderBolt Mobius TB2, and the backup SSD is Samsung SSD 850 EVO 1TB.

Thoughts? Questions? Help!

 

[appltech]

Hi! It looks like you're trying to use external bootable OS, but macOS doesn't see it as native. Do you get messages next time you boot to macOS, like about startup security settings?
I'd go to recovery mode again and check "Startup Security" there to see what's going on. There's a chance settings in that menu don't allow you to boot from external media (provided that your mac has a security chip).

 

[Hombre53]

Just a suggestion, try version 5 of CCC. I also downgraded to Catalina from Big Sur for the same reason. Version 5 works fine for making bootable clone external drives on Catalina.

 

[saudor]

If you use the beta 3.5 version of superduper, you can make bootable backups on Big Slur. You just need to make sure on the intial backup, you choose "Erase destination drive" under options. After that, you can make incremental backups but you need to do it again every time you update macOS as the system volume doesnt get copied over otherwise