Message type: E = Error
Message class:  CNV_20100 - Messageclass for chart of account conversion 
Message number: 042
Message text: &1 &2 is neither an existing G/L account nor a cost element
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The SAP error message CNV_20100042 indicates that the system is unable to find a specified General Ledger (G/L) account or cost element during a data migration or conversion process. This error typically arises in the context of using the SAP Conversion Tools, particularly during the migration of financial data.
Cause: Non-Existent G/L Account or Cost Element: The specified G/L account or cost element does not exist in the target system. This could be due to: Incorrect account numbers being used in the migration data. The accounts not being created in the target system prior to the migration. Typographical errors in the account or cost element identifiers.
Configuration Issues: The G/L account or cost element may not be properly configured in the system, or it may not be active. Data Mapping Issues: There may be issues with how the data is mapped from the source system to the target system, leading to references to accounts that do not
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