Solution : https://service.sap.com/sap/support/notes/718329 (SAP Service marketplace login required)
Key words : 
code page conversion failed              rc = 2the tables affected, single code page system reason, single code page system, single code page systems, primary key table access, 'zcheck_umgcctl' abap report attached, umgcctl export control table, system code page, db key      dsyoh, r3load log file
Related Notes : 
       
| 800791 | IBM i: In-place Code Page Conversion ASCII to Unicode | 
| 765475 | Unicode Conversion: Troubleshooting |