Shipment volume & fails to meet minimum volume of &

What causes this issue?

The system has generated a shipment whose total volume is lower than
the minimum volume.
This means that the shipment document was not created and the delivery
has not been assigned to a shipment.

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?

Error message extract from SAP system. Copyright SAP SE.