How To Fix WA654 - Receiver function module &: Parameter & is not optional

SAP Error Message - Details

• Message type: E = Error

• Message class: WA - Messages from Workflow Event Manager

• Message number: 654

• Message text: Receiver function module &: Parameter & is not optional

What causes this issue?

The specified parameter of the specified receiver function module is
not optional. Since it is not filled when SWE_EVENT_CREATE is called,
this is not allowed.

System Response

The action was terminated, the event was not triggered.

How to fix this error?

Define the specified parameter as optional and assign it a standard
value.

Error message extract from SAP system. Copyright SAP SE.