How To Fix MILL_PC327 - Assignment can no longer be changed as GR already exists

MILL_PC327 - Overview

• Message type: E = Error

• Message class: MILL_PC - Mill: Message Pool for Confirmations

• Message number: 327

• Message text: Assignment can no longer be changed as GR already exists

copied from HM6

What causes this issue?

You tried to remove the assignment of a process batch to an order item.
This is not possible, because a goods receipt has already been posted
for this order item.

System Response

The system cancels the function.

How to fix this error?

If you need to remove the assignment, you must first cancel the goods
receipt. You can then remove the assignment between the process batch
and the order item.
If you enter goods receipts for an order using the confirmation
(CO11N), you must cancel the confirmation in which you posted the goods
receipt, and all subsequent functions, using the function <ZK>Cancel
confirmation for production order</> (CO13).
If you enter goods receipts for an order using the goods movement
transactions for inventory management (for example, transaction MIGO),
you must cancel the relevant material document.

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.

MILL_PC327 - Details

• The SAP error message MILL_PC327 ("Assignment can no longer be changed as GR already exists") typically occurs in the context of production planning and materials management, particularly when dealing with production orders and goods receipts (GR). This error indicates that an attempt is being made to change an assignment (such as a component assignment to a production order) after a goods receipt has already been posted for that production order.
  
  Cause:
  The primary cause of this error is that once a goods receipt has been posted for a production order, the system locks certain aspects of that order to maintain data integrity. This means that you cannot change the assignment of components or other related data because it could lead to inconsistencies in inventory and accounting records.
  
  Solution:
  To resolve this error, consider the following steps:
  
  
  Check the Status of the Production Order: Verify the status of the production order. If the order is already