Message type: E = Error
Message class:  FKK_ID_XX_ODN - ODN message 
Message number: 023
Message text: Function module not defined
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The SAP error message FKK_ID_XX_ODN023: Function module not defined typically indicates that the system is trying to call a function module that does not exist or is not properly defined in the SAP system. This can occur in various contexts, particularly in the area of contract accounts receivable and payable (FI-CA) or related financial processes. Causes: Missing Function Module: The function module that the system is trying to call is not available in the SAP system. This could be due to a missing transport or an incomplete installation of a component. Incorrect Configuration: The system configuration may be pointing to a function module that has been renamed or removed. Custom Development: If there are custom developments or enhancements, the function module may have been deleted or not properly activated. System Upgrade: After an upgrade, some function modules may not be available if they were deprecated or replaced. Solutions: Check Function Module Existence: Use transaction code SE37 to check
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