How To Fix MEPO056 - You cannot change main and sub-items &1 simultaneously

MEPO056 - Overview

• Message type: E = Error

• Message class: MEPO - New Purchase Order Dialog

• Message number: 056

• Message text: You cannot change main and sub-items &1 simultaneously

What causes this issue?

You have only confirmed the changed data after making changes in both
the main item and the associated sub-item.
This is not allowed, since these may produce data constellations that
are not desired (e.g. different units of measure in a main item and its
sub-items).

System Response

The changed data will be adopted by the system.

How to fix this error?

Check the data in the main and sub-items and change it if necessary as
described below.
If you want to change both a main item and its associated sub-item at
the same time, proceed as follows:
Change the main item
Confirm the changes
Change the sub-item

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.

MEPO056 - Details

• The SAP error message MEPO056, which states "You cannot change main and sub-items &1 simultaneously," typically occurs in the context of purchasing documents, particularly when dealing with purchase orders or contracts that have both main items and sub-items.
  
  Cause:
  This error arises when a user attempts to make changes to both the main item and its associated sub-items at the same time. In SAP, main items and sub-items are treated differently, and the system does not allow simultaneous modifications to ensure data integrity and consistency.
  
  Solution:
  To resolve this error, you should follow these steps:
  
  
  Identify the Items: Determine which main item and sub-item you are trying to change. You can usually find this information in the error message itself or by reviewing the document in question.
  
  
  Separate Changes: Make changes to either the main item or the sub-item, but not both at the same time. For example:
  
  If you need to change the main item, do