Message type: E = Error
Message class:  CNV_PE_TPM - Messages within transport management functions 
Message number: 026
Message text: Transformation rule &1 is not included
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The SAP error message CNV_PE_TPM026 indicates that a transformation rule specified in a data migration or transformation process is not included in the current configuration or setup. This error typically arises during data migration projects, especially when using tools like SAP S/4HANA Migration Cockpit or other data transformation tools.
Cause: Missing Transformation Rule: The specified transformation rule (&1) is not defined in the system or is not included in the current migration project. Incorrect Configuration: The transformation rules may not have been properly configured or activated in the system. Version Mismatch: The transformation rules may be version-specific, and the version you are using may not support the specified rule. Data Mapping Issues: There may be issues with the data mapping that prevent the transformation rule from being recognized.
Solution: Check Transformation Rules: Verify that the transformation rule specified in the error message is correctly defined in the system. You can do this by checking the relevant configuration
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