Full delivery is required

What causes this issue?

The partial delivery specification in the order item referred to
requires that the total item quantity is delivered (partial delivery
C). The quantity to be delivered is compared with the quantity
available in the delivery.

System Response

The order item cannot be delivered due to this partial delivery
specification.

How to fix this error?

Contact the sold-to party or carry out another availability check for
this item or carry out manual backorder processing (requir.: individual
requirements).
(Path: Sales menu --> Environment --> Backorders --> Backorder
processing)
<DS:CHAP.STEUERBARE_MSG_POS_E>This system message is controllable</>

Error message extract from SAP system. Copyright SAP SE.