Hi Murat,
SAP OSS rfc would connect your solution manager system with SMP and it is working fine.
Your error log says problem with the backend system. The RFCs from solman to your ECC system for which your are generating stack file for upgrade is having issues.
I would suggest you to check all the RFCs to and from ECC and Solman. do not reply on RFC wizard but use SM59 to check all the RFCs.
These connections need to be perfect for MOPZ would check your target systems current stack.
Let me know what is the output.
Hope it helps!!
-AC