Error in document flow to add-on document

What causes this issue?

An error occurred in the area of the enhancement documents.

System Response

The error was ignored.

How to fix this error?

INCLUDE ISR_VERWALTUNG

Procedure for System Administrators

In BADI "WB2_ADDON_FLOW" method "read_flow", a reference was read to a
follow-on document with a <DS:DE.WB2_DOC_TYPE>document type</> that
does not start with the letter 'Z'. <DS:DE.WB2_DOC_TYPE>Document types
</> 'Z1' to 'ZZ' are defined for enhancement documents. Correct your
BADI implementation.
Source document: &v1&, item &v2&
Follow-on document: &v3& item &v4&.

Error message extract from SAP system. Copyright SAP SE.