Solution : https://service.sap.com/sap/support/notes/1687119 (SAP Service marketplace login required)
Key words : 
prerequisites program error solution kindly apply, symptom multiple workflow tasks, terms process control 3, attached correction instruction, multiple workflow, single isse, planner reason
Related Notes : 
       
| 1657664 | Process Control 10.0 Support Package 08- Master Note |