How To Fix SMT_CONFIG121 - Field &1 is already specified as a change structure key field

SAP Error Message - Details

• Message type: E = Error

• Message class: SMT_CONFIG - Configuration message class

• Message number: 121

• Message text: Field &1 is already specified as a change structure key field

Self-Explanatory Message

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To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.

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Smart SAP Assistant

• What is the cause and solution for SAP error message SMT_CONFIG121 - Field &1 is already specified as a change structure key field ?

  The SAP error message SMT_CONFIG121 indicates that there is a conflict in the configuration of a change structure in the SAP system. Specifically, it means that the field specified (denoted as &1 in the error message) is already defined as a key field in the change structure, and you are attempting to define it again, which is not allowed.
  Cause:
  
  Duplicate Key Field Definition: The field you are trying to add or modify is already defined as a key field in the change structure.
  Configuration Error: There may be an error in the configuration settings where the same field is being referenced multiple times as a key field.
  
  Solution:
  To resolve this error, you can follow these steps:
  
  
  Check Change Structure Configuration:
  
  Go to the relevant transaction (e.g., SMT1 for change structures) and review the configuration of the change structure.
  Look for the field specified in the error message and verify its current status as a key field.
  
  
  
  Remove Duplicate Definition:
  
  If the field is already defined as a key field, you do not need to add it again. Remove any duplicate entries or adjust your configuration to ensure that each key field is only defined once.
  
  
  
  Adjust Key Fields:
  
  If you need to change the key fields, you may need to remove the existing key field definition and then add the desired fields as key fields again.
  
  
  
  Consult Documentation:
  
  Review SAP documentation or help resources related to change structures and key fields for additional guidance on proper configuration.
  
  
  
  Testing:
  
  After making the necessary changes, test the configuration to ensure that the error no longer occurs and that the change structure behaves as expected.
  
  
  
  Related Information:
  
  Change Structures: Change structures are used in SAP to manage changes to data in a structured way, often in the context of data migration or data replication.
  Key Fields: Key fields are essential for uniquely identifying records in a database table or structure. In change structures, they play a critical role in ensuring data integrity and consistency.
  SAP Notes: Check for any relevant SAP Notes that may provide additional insights or solutions related to this error message.
  
  If the issue persists after following these steps, consider reaching out to your SAP support team or consulting with an SAP expert for further assistance.