How To Fix TT123 - Source and target cannot be in the same function

SAP Error Message - Details

• Message type: E = Error

• Message class: TT - Extended Computer Aided Test Tool (eCATT) messages

• Message number: 123

• Message text: Source and target cannot be in the same function

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message TT123 - Source and target cannot be in the same function ?

  The SAP error message TT123 ("Source and target cannot be in the same function") typically occurs in the context of data transformation or mapping within SAP systems, particularly when using tools like SAP Data Services or SAP BW (Business Warehouse). This error indicates that there is an attempt to map or transform data from a source and target that are defined within the same function or context, which is not allowed.
  Cause:
  
  Same Function Context: The error arises when both the source and target of a data transformation are defined within the same function or operation. This can happen if you are trying to read from and write to the same data structure or object in a single transformation step.
  Incorrect Mapping: The mapping configuration may be incorrectly set up, leading to a situation where the system interprets the source and target as being the same.
  
  Solution:
  
  Separate Functions: Ensure that the source and target are defined in separate functions or contexts. You may need to create a new function or use a different transformation step to handle the data flow.
  Review Mapping Logic: Check the mapping logic in your data transformation. Make sure that the source and target are distinct and not overlapping in the same function.
  Use Intermediate Steps: If necessary, introduce intermediate steps or temporary storage to facilitate the data transformation without violating the rule of having the same source and target.
  Consult Documentation: Refer to the specific SAP documentation for the tool you are using (e.g., SAP Data Services, SAP BW) for guidelines on proper mapping and transformation practices.
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any specific patches or updates related to this error message. Sometimes, there may be known issues or fixes provided by SAP.
  Community Forums: Engage with SAP community forums or support channels where other users may have encountered similar issues and can provide insights or solutions.
  Training and Documentation: If you are frequently working with data transformations in SAP, consider additional training or reviewing documentation to better understand the constraints and best practices.
  
  By addressing the cause of the error and implementing the suggested solutions, you should be able to resolve the TT123 error and successfully complete your data transformation tasks.