How To Fix VT621 - The assignment and reference number fields must be ' ' or E

SAP Error Message - Details

• Message type: E = Error

• Message class: VT - Vertriebstabellen

• Message number: 621

• Message text: The assignment and reference number fields must be ' ' or E

What causes this issue?

In the controls for copying billing document (F2) from credit memo (CR)
or debit memo (DR) the assignment number and reference number fields
should be ' ' or contain 'E'.
This message appears if VBTYP for the source document is 'M' and VBTYP
for the target billing document is '0' or 'P'. This copy control means
that the billing document is created directly from a credit memo or a
debit memo.

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?

Leave the assignment number and reference number field blank or enter
'E'.

Error message extract from SAP system. Copyright SAP SE.