Message type: E = Error
Message class:  CNV_20200_CHECK - Messages for check functions (company code merge) 
Message number: 121
Message text: The fiscal year variant is different on non-leading ledger level
The fiscal year variant is different on non-leading ledger level.
Error
You cannot run the transformation solution Company Code Merge because
certain prerequisites have not been met. We recommend that you contact
SAP for support by creating a ticket using component CA-LT-CNV.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message CNV_20200_CHECK121 indicates that there is a mismatch in the fiscal year variant between the leading ledger and the non-leading ledger in your SAP system. This error typically arises during data migration or system conversion processes, particularly when using the SAP S/4HANA Migration Cockpit or similar tools.
Cause: Fiscal Year Variant Mismatch: The fiscal year variant defined for the leading ledger (usually the primary ledger) is different from that defined for one or more non-leading ledgers. This can happen if the ledgers are configured with different fiscal year settings, which can lead to inconsistencies in financial reporting and data integrity.
Configuration Issues: The fiscal year variants may have been set up incorrectly during the initial configuration of the ledgers, or changes may have been made to one ledger without corresponding changes to the others.
Solution: To resolve this error, you need to ensure that the fiscal year variants for all ledgers are
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