How To Fix 1M128 - Balancing: Key date is before posting date. Changes not allowed

1M128 - Overview

• Message type: E = Error

• Message class: 1M - BKK: Abschluß

• Message number: 128

• Message text: Balancing: Key date is before posting date. Changes not allowed

What causes this issue?

Since postings already exist for the new period, meaning that item
counters can already be updated, changing the key date is no longer
possible.

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?

First execute an account balancing.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message 1M128 - Balancing: Key date is before posting date. Changes not allowed ?

  The SAP error message 1M128 ("Balancing: Key date is before posting date. Changes not allowed") typically occurs in the context of financial postings, particularly when dealing with document changes or adjustments in the SAP system. This error indicates that the key date (the date you are trying to use for a transaction or adjustment) is earlier than the posting date of the document you are trying to modify. 
  
  Cause:
  
  Key Date vs. Posting Date: The key date is often used for determining the validity of a transaction or for reporting purposes. If the key date is set to a date that is earlier than the posting date of the document, SAP will not allow changes to be made to ensure data integrity and compliance with accounting principles.
  Document Status: The document may be in a status that does not allow changes, such as being posted to a closed period.
  Configuration Settings: Certain configuration