Purchase order item was not confirmed or was only partially confirmed

What causes this issue?

You are processing a stock transport order item and have run an
availability check without replenishment lead time. The supplying plant
could not confirm or could only partially confirm the requested
quantity.
In the Customizing activity <DS:SIMG.SIMG_OLME_VV_161V_VF>Assign
Delivery Type and Checking Rule</>, you have selected the
<DS:DE.ATPCONFMRP>ATP Conf. MRP</> checkbox for a combination of
document type, supplying plant, and checking rule, and have thereby
defined that MRP only refers to confirmation schedule lines. As a
result, you can only save stock transport order items in which the
system has generated the corresponding confirmation schedule lines for
all request schedule lines.

System Response

How to fix this error?

Run the availability check with replenishment lead time by deselecting
the appropriate checkbox in the <DS:SIMG.SIMG_OLME_V_441V>Define
checking rule</> Customizing activity. If you want the availability
check to refer to request schedule lines, deselect the <ZK>ATP Conf. MRP
</> checkbox in the Customizing activity <ZK>Assign Delivery Type and
Checking Rule</>.
You can save the stock transport order if you select the
<DS:DE.ME_FIXMG>Fixed Date and Qty</> checkbox at item level. If
required, the system then creates another stock transport order for the
unconfirmed quantity during the next planning run.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.