How To Fix WL423 - Error in resolution of rule '&1' for step '&2'

SAP Error Message - Details

• Message type: E = Error

• Message class: WL - Workflow: run-time messages

• Message number: 423

• Message text: Error in resolution of rule '&1' for step '&2'

What causes this issue?

The function module for rule '&V1&' initialized an exception and
returned a message ("MESSAGE ... [RAISING ...]").

System Response

If the message is of type 'A', 'E' or ' ', the confirmation of the
current work item is recorded and the work procedure set to <ZH>error
</> status.
In all other cases, the message is logged as a warning and the work
procedure continues.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.