Message type: E = Error
Message class:  CNV_PE - General messages for posting engine 
Message number: 551
Message text: Type of extension not defined
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The SAP error message CNV_PE551: Type of extension not defined typically occurs during data migration or conversion processes, particularly when using the SAP Landscape Transformation (SLT) or SAP Data Services tools. This error indicates that the system is unable to find a defined extension type for a specific operation or data object. Causes: Missing Configuration: The extension type may not be defined in the configuration settings of the data migration tool you are using. Incorrect Mapping: There may be an issue with the mapping of the data fields, where the system expects a certain type of extension that has not been set up. Version Compatibility: The error could arise if there are compatibility issues between the version of the tools being used and the SAP system. Custom Development: If there are custom developments or enhancements in the system, they may not be properly integrated or defined. Solutions: Check Configuration: Review the configuration settings in the data migration
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