How To Fix OL804 - CallBack function '&' not defined

SAP Error Message - Details

• Message type: E = Error

• Message class: OL - Workflow object types: Run-time system

• Message number: 804

• Message text: CallBack function '&' not defined

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message OL804 - CallBack function '&' not defined ?

  The SAP error message OL804, which states "CallBack function '&' not defined," typically occurs in the context of SAP ABAP programming, particularly when dealing with function modules or methods that are expected to call a callback function that has not been defined or is not accessible in the current context.
  Cause:
  
  Undefined Callback Function: The callback function that is being referenced in the code is not defined in the program or is misspelled.
  Scope Issues: The callback function may be defined in a different scope or context that is not accessible from where it is being called.
  Incorrect Function Signature: The function signature of the callback may not match what is expected, leading to the system not recognizing it.
  Missing Includes or Libraries: If the callback function is part of an include or library that has not been included in the program, it will not be recognized.
  
  Solution:
  
  Check Function Definition: Ensure that the callback function is defined in the program or class where it is being called. Verify the spelling and case sensitivity.
  Scope Verification: Make sure that the callback function is accessible from the point where it is being called. If it is defined in a different class or program, ensure that the necessary references are made.
  Review Function Signature: Check that the parameters and return types of the callback function match what is expected in the calling context.
  Include Necessary Libraries: If the callback function is part of an include or library, ensure that it is properly included in your program.
  Debugging: Use debugging tools to trace the execution and see where the callback function is expected to be called and why it is not found.
  
  Related Information:
  
  Documentation: Refer to SAP documentation for the specific function module or method you are working with to understand the expected callback functions.
  SAP Community: Engage with the SAP Community forums or support channels for additional insights or similar issues faced by other developers.
  ABAP Development Guidelines: Familiarize yourself with best practices in ABAP development, especially regarding function modules and callback mechanisms.
  
  By following these steps, you should be able to identify and resolve the issue related to the OL804 error message in SAP.