How To Fix SMT_CONFIG123 - Field &1 cannot be used as a key field

SAP Error Message - Details

• Message type: E = Error

• Message class: SMT_CONFIG - Configuration message class

• Message number: 123

• Message text: Field &1 cannot be used as a key field

Self-Explanatory Message

Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.

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.

Unfortunately, there isn't any extra information in this error notice.

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Smart SAP Assistant

• What is the cause and solution for SAP error message SMT_CONFIG123 - Field &1 cannot be used as a key field ?

  The SAP error message SMT_CONFIG123, which states "Field &1 cannot be used as a key field," typically occurs in the context of configuring data transfer or replication scenarios, particularly when working with SAP Landscape Transformation (SLT) or similar tools. This error indicates that the field you are trying to designate as a key field does not meet the necessary criteria for being a key field in the context of the configuration.
  Causes:
  
  Field Characteristics: The field you are trying to use as a key may not have the required characteristics, such as being unique or not nullable.
  Data Type Issues: The data type of the field may not be compatible with key field requirements.
  Field Length: The length of the field may exceed the maximum allowed length for key fields.
  Field Usage: The field may already be used in another context or configuration where it cannot be designated as a key.
  Technical Settings: The technical settings of the field in the underlying database table may not allow it to be used as a key.
  
  Solutions:
  
  Check Field Properties: Review the properties of the field in the data dictionary (SE11) to ensure it meets the requirements for a key field (e.g., unique, not nullable).
  Change Field Type: If the field type is not suitable, consider changing it to a compatible type or using a different field that meets the criteria.
  Adjust Field Length: If the field length is an issue, you may need to adjust it to fit within the allowed limits for key fields.
  Use Alternative Fields: If the field cannot be used as a key, consider using another field that meets the criteria for uniqueness and non-nullability.
  Consult Documentation: Refer to SAP documentation or help resources for specific requirements regarding key fields in the context of your configuration.
  
  Related Information:
  
  SAP Notes: Check for any relevant SAP Notes that may address this specific error or provide additional guidance.
  SLT Configuration: If you are working with SLT, review the configuration settings and ensure that the source and target tables are correctly defined.
  Data Model: Ensure that your data model is designed correctly, with appropriate primary keys defined in the source tables.
  Testing: After making changes, test the configuration to ensure that the error is resolved and that data transfer or replication works as expected.
  
  If the issue persists after trying the above solutions, consider reaching out to SAP support or consulting with an SAP expert for further assistance.