How To Fix FKKBIX639 - The interface of function module &1 is not correct

SAP Error Message - Details

• Message type: E = Error

• Message class: FKKBIX - Conv.Inv.: Billing (Invoice Preprocessing)

• Message number: 639

• Message text: The interface of function module &1 is not correct

What causes this issue?

Make sure that you use the templates described in the following links:
<DS:DE.DISC_BASE_EXIT_KK>Determination of the base quantity using a
function module</>
<DS:DE.DISC_CALC_RULE_EXIT_KK>Calculation rule in function module</>
<DS:DE.DISC_COND_RULE_EXIT_KK>Condition rule in function module</>

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message FKKBIX639 - The interface of function module &1 is not correct ?

  The SAP error message FKKBIX639 indicates that there is an issue with the interface of a function module. This error typically arises when the parameters defined in the function module do not match the expected parameters in the calling program or when there are inconsistencies in the data types or structures.
  Cause:
  
  Mismatch in Parameters: The function module being called has parameters that do not match the expected parameters in the calling program. This could be due to changes in the function module interface that have not been reflected in the calling program.
  Data Type Issues: The data types of the parameters being passed may not be compatible with those defined in the function module.
  Missing Parameters: Required parameters may be missing in the call to the function module.
  Changes in Function Module: If the function module was recently modified (e.g., added or removed parameters), the calling program may not have been updated accordingly.
  
  Solution:
  
  Check Function Module Interface: Go to transaction SE37 (Function Builder) and check the interface of the function module mentioned in the error message. Verify the parameters and their data types.
  Update Calling Program: If there are discrepancies between the function module interface and the calling program, update the calling program to match the function module's interface.
  Check for Missing Parameters: Ensure that all required parameters are being passed to the function module.
  Data Type Compatibility: Make sure that the data types of the parameters being passed are compatible with those defined in the function module.
  Consult Documentation: If the function module is part of a standard SAP package, consult the SAP documentation or release notes for any changes that may have been made to the function module.
  Testing: After making the necessary changes, test the calling program to ensure that the error is resolved.
  
  Related Information:
  
  Transaction Codes: SE37 (Function Builder), SE80 (Object Navigator), SE11 (Data Dictionary).
  Debugging: Use the debugger to step through the code and identify where the error occurs.
  SAP Notes: Check the SAP Support Portal for any relevant SAP Notes that may address this specific error or provide additional guidance.
  Version Control: If you are working in a development environment, ensure that you are using the correct version of the function module and that all changes are properly transported to the relevant systems (e.g., QA, Production).
  
  By following these steps, you should be able to identify and resolve the issue causing the FKKBIX639 error message in SAP.