Message type: E = Error
Message class:  CNV21500 - Messages for HR conversions basis 
Message number: 037
Message text: Import routine is fun. mod., but structure of RELID <&1, &2> not in DDIC
Import routine indicated in CNV_INDX_MACROS for RELID <&v1&, &v2&
> is function module, but structure of this RELID is not in defined in
DDIC.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
For this RELID you probably must use macros to import data. Please
maintain CNV_INDX_MACROS and CNV_INDX_MACPARS tables correctly.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message CNV21500037 indicates that there is an issue with the import routine in a conversion process, specifically that the structure associated with the given RELID (which typically refers to a specific data structure or object) is not found in the Data Dictionary (DDIC). This can occur during data migration or conversion processes, particularly when using SAP's data migration tools.
Cause: Missing Structure: The structure defined by the RELID is not present in the Data Dictionary. This could be due to: The structure not being created or activated. The structure being deleted or renamed. A mismatch in the naming or version of the structure. Incorrect Configuration: The configuration for the import routine may be pointing to an incorrect or outdated structure. Transport Issues: If the structure was recently transported from another system, it may not have been successfully imported into the target system.
Solution: Check Data Dictionary: Go to transaction SE11 (Data Dictionary) and check if the
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