How To Fix DMC_EXCEPTION003 - Structure &1 cannot be a lookup table; it is mapped to target structures

SAP Error Message - Details

• Message type: E = Error

• Message class: DMC_EXCEPTION - Message class for exception texts

• Message number: 003

• Message text: Structure &1 cannot be a lookup table; it is mapped to target structures

A lookup table contains records that are looked up from a field in
another table to fill in the value of that field. The table can be
referenced by rules and used by mapping operations, but does not
directly provide content for fields in the target system.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message DMC_EXCEPTION003 - Structure &1 cannot be a lookup table; it is mapped to target structures ?

  The SAP error message DMC_EXCEPTION003 indicates that there is an issue with the data mapping in the Data Migration Cockpit (DMC) where a structure is being treated as a lookup table, but it is already mapped to target structures. This typically occurs during data migration processes when the system expects a certain configuration for the data structures involved.
  Cause:
  
  Incorrect Mapping: The structure in question is likely being used in a way that conflicts with its intended use as a lookup table. Lookup tables are generally used to provide reference data, while target structures are meant to hold the actual data being migrated.
  Configuration Issues: There may be a misconfiguration in the data migration settings or the way the structures are defined in the DMC.
  Duplicate Usage: The same structure might be mapped to multiple target structures, which can lead to confusion in how the data should be processed.
  
  Solution:
  
  Review Mapping: Check the mapping configuration in the Data Migration Cockpit. Ensure that the structure is not being incorrectly defined as a lookup table if it is already mapped to target structures.
  Adjust Structure Definitions: If the structure is intended to be a lookup table, ensure that it is not mapped to any target structures. If it needs to be a target structure, then it should not be defined as a lookup table.
  Consult Documentation: Refer to SAP documentation or guides related to the Data Migration Cockpit for best practices on defining and mapping structures.
  Test Changes: After making adjustments, test the migration process again to ensure that the error is resolved.
  
  Related Information:
  
  Data Migration Cockpit (DMC): This is a tool provided by SAP to facilitate the migration of data from legacy systems to SAP S/4HANA or other SAP systems.
  Lookup Tables: These are tables that provide reference data and are typically used to ensure data integrity and consistency during data migration.
  Target Structures: These are the structures in the target system where the migrated data will be stored.
  
  If the issue persists after following these steps, it may be beneficial to consult with SAP support or a technical consultant who specializes in data migration processes.