Message type: E = Error
Message class:  CNV_PE - General messages for posting engine 
Message number: 864
Message text: MWB attribute of table &1 is removed
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The SAP error message CNV_PE864 indicates that an attribute of a table has been removed in the context of a data migration or conversion process, typically related to the SAP S/4HANA migration or other data transformation projects. This message is part of the SAP Conversion and Migration tools, which are used to facilitate the transition from older SAP systems to newer versions or to S/4HANA.
Cause: The error occurs when: An attribute (field) that was previously part of a table is no longer available in the target system or the target version of the table. This can happen due to changes in the data model, such as the removal of obsolete fields or changes in the structure of the database tables during the migration process.
Solution: To resolve this error, you can take the following steps: Check the Migration/Conversion Documentation: Review the SAP documentation related to the specific migration or conversion process you are undertaking. This documentation
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