Message type: E = Error
Message class:  CNV20551 - message for package 20551 (company code delete) 
Message number: 821
Message text: No Data exists in table for the entered key fields
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The SAP error message CNV20551821: No Data exists in table for the entered key fields typically occurs during data migration or conversion processes, particularly when using SAP's Data Migration tools or during the execution of certain transactions that require data to be present in specific tables.
Cause: Missing Data: The most common cause of this error is that the key fields you are trying to access do not have any corresponding entries in the database table. This could be due to: Data not being loaded or migrated properly. Incorrect key field values being used in the query or transaction. Data being deleted or not yet created in the system. Incorrect Configuration: Sometimes, the configuration settings for the migration or conversion process may not be set up correctly, leading to attempts to access non-existent data. Timing Issues: If the data migration is being performed in stages, it’s possible that the data you are trying to access has not
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