Solution : https://service.sap.com/sap/support/notes/661785 (SAP Service marketplace login required)
Key words :
deregulation process 'outgoing invoice/incoming payment', error message ez800 'internal error, create parameter 'invoice form', invoice form parameter', service provider arrangement, attached correction instructions, program error, parameter x_formkey, fm efg_check_screen_formkey', edereg453 'initial
Related Notes :
| 650152 | Known corrections for IS-U/CCS 4.64 AOSP017 |