How To Fix W8020 - The interface of function module '&1' does not correspond to conventions

SAP Error Message - Details

• Message type: E = Error

• Message class: W8 - Workflow: Expressions, data flow

• Message number: 020

• Message text: The interface of function module '&1' does not correspond to conventions

What causes this issue?

Function module &VA1& does not correspond to the convention for program
exit for dataflows. The function modules for dataflow have an adjusted
interface which must be as follows:
Import parameters
DATAFLOW with reference SWABINDEF-DATAFLOW
Table parameters
CALLED_CONTAINER with structure SWCONT
CALLING_CONTAINER with structure SWCONT

How to fix this error?

You should adjust the binding function module to accord with this
convention or use the function module SWA_TEMPLATE_EXECUTE_DATAFLOW as
a copy model.

Error message extract from SAP system. Copyright SAP SE.