Partner Function is not allowd for source structure &1

What causes this issue?

The partner function can only be used with source structures
WLF_KOMWBPA_HEAD and WLF_KOMWBPA_ITEM.

System Response

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

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.