Message type: E = Error
Message class:  CNV_21527 - Logical System Rename 
Message number: 020
Message text: Logical system &1 not defined in TBDLS
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The SAP error message CNV_21527020 indicates that a logical system is not defined in the table TBDLS. This table is used in SAP to manage logical system definitions, which are essential for various processes, including data transfer and system integration.
Cause: The error typically occurs due to one of the following reasons: The logical system you are trying to use has not been created or defined in the SAP system. There may be a typo or mismatch in the logical system name being referenced. The logical system might have been deleted or not properly configured in the system.
Solution: To resolve this error, you can follow these steps: Check Logical System Configuration: Go to transaction code SE03 (Transport Organizer Tools) or BD54 (Maintain Logical Systems). Verify if the logical system mentioned in the error message is listed in the table TBDLS. If it is not present, you will need to create it. Create a Logical System: If the logical system is missing, you
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