Upgrade from SLES 12 SP 5 to SLES 15 SP 2 with SUMA 4.3

Hi
I’m trying to upgrade SLES 12 SP5 to SLES 15 SP2. I have followed the guide on Client - Major Version Upgrade :: SUSE Manager Documentation.

  • Updating the installer > done
  • preparing system for automatic installation > done
  • system probing > done
  • preparing system for automated installation > done but there is an error

These packages cannot be found in the software repositories: autoyast2: The package is not available autoyast2-installation: The package is not available

  • preparing system for automated installation > done but the result booting error missing operating system.

Can you please kindly help to solve this issue? or another template for reference in detail?

Regards
Donkus