Company code &, transaction &: Flow is not an additional flow

What causes this issue?

In the context of an external data transfer, only additional flows may
be transferred (flow category: 'additional flow/condition').

System Response

The transaction has been marked as containing errors and can not be
processed.

How to fix this error?

Check your Customizing settings as related to flow types. Correct the
erroneous data record or make the necessary adjustments in Customizing.

Error message extract from SAP system. Copyright SAP SE.