Message type: E = Error
Message class:  RSO_RES_CONVMSGS - Messages directly related to the conversion types 
Message number: 028
Message text: Key date derivation type &1 already exists.
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The SAP error message RSO_RES_CONVMSGS028 indicates that there is an issue with the key date derivation type in the context of SAP BW (Business Warehouse) or SAP BI (Business Intelligence). This error typically occurs when you are trying to create or modify a key date derivation type that already exists in the system.
Cause: The error is caused by attempting to define a key date derivation type that has already been defined in the system. This can happen if: You are trying to create a new key date derivation type with the same identifier as an existing one. There is a duplicate entry in the configuration settings.
Solution: To resolve this error, you can take the following steps: Check Existing Key Date Derivation Types: Go to the relevant transaction in SAP (e.g., RSA1 for Data Warehousing Workbench). Navigate to the area where key date derivation types are defined. Look for the key date derivation type that you are trying to
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