In rare case, administrator might experience RFC error during the client copy process.
Steps to create the RFC for client copy:
1) TCODE: SCCL and sample screen of client copy
2) Subsequent screen of the client copy
3) Error occur on the client copy
4) Login to client: 000 with DDIC or SAP* or any administration account and execute TCODE: SM59 to create a RFC connection for the source client (FINBTR@<SID>CLNT<SourceClient>)
5) Used a login account with "sap_all" in the source client and test the connection with "Remote Logon" and "Connection Test" button
6) Continue the client copy process and the error on "step 3" should be resolve
