Solution : https://service.sap.com/sap/support/notes/881048 (SAP Service marketplace login required)
Key words :
DDSHPVAL50, ASSIGN_CAST_WRONG_LENGTH, Unicode
Related Notes :
| 1319517 | Unicode Collection Note |
| 1275149 | Input help (F4): Preparing the Unicode conversion |
| 679456 | Reducing data volume before Unicode Conversion |
| 551344 | Unicode Conversion Documentation |