Delivery quantity is less than quantity of &1 &2 assigned to batches

What causes this issue?

The delivery quantity is smaller than the quantity assigned to the
<GL:batch>batches</>.
INCLUDE 'NA_NO_PROCESSING_1' OBJECT DOKU ID TX LANGUAGE E

System Response

First reduce the quantity assigned to the batches before you reduce the
delivery quantity.

Error message extract from SAP system. Copyright SAP SE.