Solution : https://service.sap.com/sap/support/notes/420114 (SAP Service marketplace login required)
Key words : 
additional key words business explorer, /general/r3server/abap/note, 1c frontend patch 11, installed frontend patch 11, 1c frontend patch 12, wdttree - type mismatch, program error occurs, bw frontend patch, 0b frontend installation, frontend patch
Related Notes : 
       
| 367280 | BW 2.0B/2.1C Frontend patch 12 | 
| 367279 | BW 2.0B/2.1C Frontend Patch 11 | 
| 309281 | BW 2.0B frontend installation of patches | 
| 197460 | BW Frontend Checktool sapbexc.xla | 
| 96885 | Downloading front end patches | 
| 13719 | Preliminary transports to customers (note for customers) |