Message type: E = Error
Message class:  CNV_20100 - Messageclass for chart of account conversion 
Message number: 129
Message text: Problem due to conversion to existing set &1, &2, &3
When simulating the set rename, the system found that an old set would
be converted into an existing set &V1&, set class &V2&, subclass &V3&.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
This would amount to merging the sets, which is not allowed.
Check your entries in the activity <ZK>Maintain Dupl. CostEl Grps/PRCTR
Acct Grps/Intervals/Sets</> and change the mapping accordingly.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message CNV_20100129 typically occurs during data migration or conversion processes, particularly when using the SAP S/4HANA Migration Cockpit or other data migration tools. This error indicates that there is a problem with the conversion of data to an existing set, which can be due to various reasons.
Cause: Duplicate Entries: The error often arises when there are duplicate entries in the source data that conflict with existing entries in the target system. Data Integrity Issues: There may be issues with data integrity, such as missing required fields or invalid data formats. Mapping Issues: The mapping of fields from the source to the target may not be correctly defined, leading to conflicts. Existing Data Conflicts: The target system may already contain data that conflicts with the incoming data, such as primary key violations.
Solution: Check for Duplicates: Review the source data for duplicates that may conflict with existing records in the target system. Remove or
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