Message type: E = Error
Message class:  CNV_DMC_SIN - Messages for s-innovations migration 
Message number: 139
Message text: Plant cannot be initial in the conversion rule &1, Planner Group is &2
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The SAP error message CNV_DMC_SIN139 indicates that there is an issue with the conversion rule related to the initial plant and planner group during a data migration or conversion process. This error typically arises in the context of using the SAP Data Migration Cockpit or similar tools for migrating data from legacy systems to SAP S/4HANA or other SAP systems.
Cause: Missing Configuration: The plant or planner group specified in the conversion rule may not be properly configured in the SAP system. Data Inconsistency: There may be inconsistencies in the data being migrated, such as missing entries for the specified plant or planner group. Incorrect Mapping: The mapping of the source data to the target data structure may be incorrect, leading to the inability to initialize the plant in the specified conversion rule. Authorization Issues: The user executing the migration may not have the necessary authorizations to access or modify the specified plant or planner
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