Solution : https://service.sap.com/sap/support/notes/82179 (SAP Service marketplace login required)
Key words : 
additional key words variant configuration, apply hot package sapkh31g11, master data list, prerequisites program error, attached advance corrections, transaction cu50, bom explosion, plan breakdown, plan object, 0f solution
Related Notes : 
       
| 85237 | 3.1I:sales order entry change BOM -> task list | 
| 85236 | 3.1I:CU50 obj.depndncs display f.standard task list | 
| 73610 | 3.1H: CU50 'Multi-level task list configuration' | 
| 73584 | 3.1H CU50: Object change BOM <-> Standard task list |