Message type: E = Error
Message class:  CNV_PE_IF_RT - PE: Interfaces Runtime generation 
Message number: 021
Message text: Structure mapping: &1
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The SAP error message CNV_PE_IF_RT021, which indicates "Structure mapping: &1," typically arises during data migration or conversion processes, particularly when using SAP's data migration tools like the SAP S/4HANA Migration Cockpit or other conversion tools. This error suggests that there is an issue with the mapping of data structures between the source and target systems.
Cause: Mapping Issues: The error often occurs when there is a mismatch in the data structure definitions between the source and target systems. This could be due to: Missing fields in the target structure that are present in the source. Data types that do not match between the source and target. Incorrectly defined mapping rules. Configuration Errors: If the configuration settings for the migration or conversion process are not set up correctly, it can lead to this error. Data Quality Issues: If the data being migrated contains inconsistencies or invalid entries that do not conform to the expected structure, it can trigger
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