How To Fix /IWBEP/CM_MGW_RT019 - Function import '&1' cannot use return type '&2' if no data is returned

SAP Error Message - Details

• Message type: E = Error

• Message class: /IWBEP/CM_MGW_RT -

• Message number: 019

• Message text: Function import '&1' cannot use return type '&2' if no data is returned

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message /IWBEP/CM_MGW_RT019 - Function import '&1' cannot use return type '&2' if no data is returned ?

  The SAP error message /IWBEP/CM_MGW_RT019 typically occurs in the context of SAP Gateway and OData services when a function import is defined to return a specific data type, but the actual implementation does not return any data. This can lead to a mismatch between the expected return type and the actual return value.
  Cause:
  
  Mismatch in Return Type: The function import is defined to return a specific type (e.g., an entity type or a complex type), but the implementation does not return any data (e.g., it returns an empty response or a different type).
  Incorrect Implementation: The logic in the function import implementation may not be correctly set up to return the expected data.
  Service Definition Issues: The OData service definition may not align with the actual implementation, leading to discrepancies in expected and returned data types.
  
  Solution:
  
  Check Function Import Definition: Review the function import definition in the OData service to ensure that the return type is correctly specified.
  Implement Data Return Logic: Ensure that the implementation of the function import returns data of the expected type. If the function is supposed to return a collection, make sure it returns an empty collection instead of no data.
  Adjust Return Type: If the function import is not supposed to return any data, consider changing the return type in the service definition to a type that does not expect data (e.g., a simple type or a status code).
  Test the Function Import: After making changes, test the function import to ensure it behaves as expected and returns the correct data type.
  Check for Errors in Implementation: Look for any logical errors in the code that might prevent data from being returned.
  
  Related Information:
  
  OData Services: Understanding how OData services work in SAP Gateway is crucial. Familiarize yourself with the concepts of function imports, entity types, and complex types.
  SAP Gateway Error Handling: Review SAP documentation on error handling in Gateway services to understand how to troubleshoot and resolve common issues.
  Debugging: Use debugging tools in SAP to step through the function import implementation and identify where the data return logic may be failing.
  SAP Notes: Check for any relevant SAP Notes that may address this specific error or provide additional guidance on function imports and return types.
  
  By following these steps, you should be able to resolve the error and ensure that your function import behaves as expected.