How To Fix AD591 - Table & already changed, 'Add fields' not allowed

SAP Error Message - Details

• Message type: E = Error

• Message class: AD - Data Dictionary application messages

• Message number: 591

• Message text: Table & already changed, 'Add fields' not allowed

What causes this issue?

The table was already active and already has another revised version
which differs from the active version. Fields from the active version
were changed in the revised version. In this situation the <LS>Append
fields</> function is not allowed.

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?

Use the field maintenance screen of the corresponding table to add
fields to the revised version.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message AD591 - Table & already changed, 'Add fields' not allowed ?

  The SAP error message AD591 indicates that you are trying to add fields to a table that has already been changed or modified in a way that prevents further changes. This typically occurs in the context of data dictionary objects in SAP, particularly when working with transparent tables or structures.
  Cause:
  
  Table Already Modified: The table you are trying to modify has already been changed in a way that does not allow further modifications, such as adding fields.
  Transport Request Issues: If the table is part of a transport request that has already been released or is in a state that does not allow further changes.
  Table Locking: The table might be locked due to ongoing development or transport activities.
  Development Class Restrictions: The table might belong to a development class that has restrictions on modifications.
  
  Solution:
  
  Check Table Status: Verify the status of the table in the Data Dictionary (SE11). If it is marked as "modified," you may need to revert or adjust the changes.
  Transport Request: Ensure that the transport request associated with the table is not released. If it is, you may need to create a new transport request for your changes.
  Unlock the Table: If the table is locked, you may need to unlock it. This can be done by checking the lock entries in transaction SM12 and removing any unnecessary locks.
  Use a New Table: If the table cannot be modified due to restrictions, consider creating a new table with the desired fields instead of modifying the existing one.
  Consult Documentation: Review SAP documentation or consult with your SAP Basis or ABAP team for specific guidelines related to your system and development environment.
  
  Related Information:
  
  Transaction Codes: 
  
  SE11: Data Dictionary
  SE09/SE10: Transport Organizer
  SM12: Display and Delete Locks
  
  
  SAP Notes: Check for any relevant SAP Notes that might address this specific error or provide additional guidance.
  Development Guidelines: Familiarize yourself with your organization's development guidelines regarding changes to database tables and objects.
  
  If the issue persists after trying the above solutions, it may be beneficial to consult with your SAP support team or refer to SAP community forums for further assistance.