How To Fix ARUN_MAIN002 - Item &1 is assigned; changing &2 will unassign the item

SAP Error Message - Details

• Message type: E = Error

• Message class: ARUN_MAIN -

• Message number: 002

• Message text: Item &1 is assigned; changing &2 will unassign the item

What causes this issue?

The material is relevant to Supply Assignment (ARun) and an assignment
exists for this document item.
The document item will be unassigned for one of the following reasons:
You have defined the Customization for the document item under
<LS>Cross-Application Components > Advanced Available-to-Promise (aATP)
> Supply Assignment (ARun) > Cross-Applications > Purchase Order
Handling</>, changing the document item will unassign the order. You
have set the field check as W = Warnings Before an Order is Unassigned.
You have not defined a rule to unassign orders under
<LS>Cross-Application Components > Advanced Available-to-Promise (aATP)
> Supply Assignment (ARun) > Cross-Applications > Purchase Order
Handling</>. The item will be unassigned automatically.

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?

Define rules to unassign orders for an application type in Customizing
under <LS>Cross-Application Components > Advanced Available-to-Promise
(aATP) > Supply Assignment (ARun) > Cross-Applications</>.
By defining a rule to unassign orders, you specify exactly how the
system should react when an application type is modified (for example,
change in requirement date, goods receipt date, plant, storage location,
and so on).
You set the appropriate fields listed in the application type in
Customizing. For field checks, you can assign one of the following
options.
N = No Action
W = Warnings Before an Order is Unassigned
E = Change Not Permitted
Depending on the selected parameter, the system decides how and when the
quantities should be unassigned.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message ARUN_MAIN002 - Item &1 is assigned; changing &2 will unassign the item ?

  The SAP error message ARUN_MAIN002 indicates that an item (denoted as &1) is currently assigned to a specific entity or process, and attempting to change another related entity (denoted as &2) will result in the unassignment of the item. This message typically arises in scenarios involving assignments in various SAP modules, such as Asset Accounting, Material Management, or Sales and Distribution.
  
  Cause:
  The error occurs when there is an attempt to modify a related object that has dependencies on the item in question. For example, if you are trying to change a master data record (like a cost center or a project) that is linked to an asset or a material, the system is warning you that this change will break the existing assignment of the item.
  
  Solution:
  To resolve this error, you can take the following steps:
  
  
  Review Assignments: Check the current assignments of the item &1. Understand what it is linked to and