Hi,
Can you first login in the current system that need to be updates.
Please check you can login with DDIC and run SPAM.
What is the version showing there.
It looks line that the SUM tool cant login or login and run the SPAM version check based on the below message . Is the Current system running. DO you see any dump in st22.
"RFC error system ARP nr 00 function 'OCS_API_GET_SPAM_VERSION' failed with code 3 key"
This phase is related to SPAM Version Check.
Can you try to kill the SUM process and rerun it again.
What is the target SPAM version that you need when the SUM tool completes this phase as ask you to go to in your earlier upgrade. Try to patch the current system to that SPAM version which you would have done it for the earlier release.
Reset the SUM tool and start the upgrade again .
Thanks
Rishi Abrol