The "delivery completed" indicator is set for the purchase order item

What causes this issue?

You are entering a partial goods receipt for a purchase order item that
is already defined as <ZK>delivery completed</>.

System Response

IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.
If your Customizing settings are such that you see an error message, you
cannot enter any further partial goods receipt for this completed
purchase order item.
ENDIF.
If the message is a warning message or information message, you can post
the partial goods receipt.
IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.
<ZH>Note</>: If you use example implementation
MB_GOODSMOVEMENT_DCI_EXAMPLE of the Business Add-Ins (BAdIs)
<DS:SIMG.MB_GOODSMOVEMENT_DCI>Set "Delivery Completed" Indicator</>,
the system does not deselect the "delivery completed" indicator, even
after you have entered the additional partial goods receipt. This means
that budget is only released for the delivery quantity of this partial
goods receipt, and not for the entire quantity of the purchase order
item that is still open.
ENDIF.

How to fix this error?

Check the delivered quantity.
If you are expecting further deliveries for this purchase order item,
deselect the "delivery completed" indicator manually.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.