How To Fix RSAR780 - Error in the prefix determination. Start value & is unknown

SAP Error Message - Details

• Message type: E = Error

• Message class: RSAR - Data Transfer and Metadata Maintenance

• Message number: 780

• Message text: Error in the prefix determination. Start value & is unknown

What causes this issue?

Incorrect call of the prefix determination for the transfer structure of
the source system. The prefix start value &V1& is not one of the
allowed values (A-Z, 0-9).

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Using the error number (ID) search for relevant notes in the SAP Support
Portal.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message RSAR780 - Error in the prefix determination. Start value & is unknown ?

  The SAP error message RSAR780, which states "Error in the prefix determination. Start value & is unknown," typically occurs in the context of SAP BW (Business Warehouse) when there is an issue with the data source or the data extraction process. This error is related to the extraction of data from a source system, and it indicates that the system is unable to determine the prefix for a certain data object.
  Causes:
  
  Missing or Incorrect Prefix Configuration: The prefix for the data source may not be defined correctly in the system, or it may be missing entirely.
  Data Source Issues: The data source from which you are trying to extract data may not be properly configured or may not exist.
  Transport Issues: If the data source was recently transported from another system, there may be inconsistencies or missing configurations.
  Authorization Issues: The user executing the extraction may not have the necessary authorizations to access the data source or the related objects.
  
  Solutions:
  
  
  Check Prefix Configuration:
  
  Go to the DataSource in the SAP BW system and check the prefix settings. Ensure that the prefix is correctly defined and that it matches the expected values.
  You can check this in the DataSource maintenance transaction (e.g., RSA1).
  
  
  
  Validate Data Source:
  
  Ensure that the data source is active and correctly configured. You can do this by checking the DataSource in the source system and ensuring that it is set up properly.
  Test the data source extraction to see if it works without errors.
  
  
  
  Transport Check:
  
  If the DataSource was recently transported, check the transport logs for any errors or warnings that might indicate issues with the transport.
  Ensure that all necessary objects related to the DataSource have been transported correctly.
  
  
  
  Authorization Check:
  
  Verify that the user has the necessary authorizations to access the DataSource and perform the extraction. This may involve checking roles and authorizations in the SAP system.
  
  
  
  Consult SAP Notes:
  
  Check the SAP Support Portal for any relevant SAP Notes that may address this specific error. There may be patches or updates that resolve known issues related to this error message.
  
  
  
  Debugging:
  
  If the issue persists, consider debugging the extraction process to identify where the prefix determination is failing. This may require technical expertise in ABAP or BW extraction processes.
  
  
  
  Related Information:
  
  Transaction Codes: RSA1 (Data Warehousing Workbench), RSA3 (DataSource Test), RSO2 (DataSource Maintenance).
  SAP Notes: Search for specific SAP Notes related to RSAR780 for any updates or fixes provided by SAP.
  Documentation: Review SAP BW documentation for best practices on DataSource configuration and troubleshooting.
  
  If the problem continues after trying these solutions, it may be beneficial to reach out to SAP support or consult with a technical expert familiar with SAP BW and data extraction processes.