How To Fix E9021 - Function &1 is unknown

SAP Error Message - Details

• Message type: E = Error

• Message class: E9 - General IS-U Error Messages

• Message number: 021

• Message text: Function &1 is unknown

What causes this issue?

You have called a function that the transaction/system does not
recognize.
Either the function is not yet implemented although a menu entry or a
pushbutton exists, or an incorrect function code is transferred to the
program (error in the SAPGUI).

System Response

The system cannot carry out the function.

How to fix this error?

Note the function code from the error message and the screen status
(can be found via <LS>System</> -> <LS>Status</>) and send a problem
message to SAP.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message E9021 - Function &1 is unknown ?

  The SAP error message E9021, which states "Function &1 is unknown," typically indicates that the system is unable to recognize a function module, method, or procedure that is being called in your ABAP code or in a specific transaction. This can occur for several reasons:
  Causes:
  
  Typographical Error: There may be a typo in the function name being called.
  Function Module Not Created: The function module may not exist in the system, possibly due to it not being created or activated.
  Authorization Issues: The user may not have the necessary authorizations to access the function module.
  Transport Issues: If the function module was recently transported from another system, it may not have been imported correctly.
  Namespace Issues: The function might be in a different namespace that is not accessible in the current context.
  Versioning: The function module may have been changed or deleted in a newer version of the software.
  
  Solutions:
  
  Check for Typos: Verify that the function name is spelled correctly in the code.
  Function Module Existence: Use transaction SE37 (Function Builder) to check if the function module exists. If it does not, you may need to create it or find out why it is missing.
  Authorization Check: Ensure that the user has the necessary authorizations to execute the function module. You can check this in transaction SU53 after the error occurs.
  Transport Logs: If the function module was recently transported, check the transport logs to ensure it was imported successfully.
  Namespace Verification: Ensure that the function module is in the correct namespace and that your program has access to it.
  Debugging: If you have access to the ABAP debugger, you can set a breakpoint before the function call to inspect the parameters and the context in which the function is being called.
  
  Related Information:
  
  Transaction Codes: 
  
  SE37: Function Module Builder
  SE80: Object Navigator
  SU53: Authorization Check
  
  
  Documentation: Check SAP Help Portal or the specific documentation for the function module if it is a standard SAP function.
  SAP Notes: Search for relevant SAP Notes in the SAP Support Portal that might address known issues related to this error message.
  
  If the issue persists after checking these areas, it may be beneficial to consult with your SAP Basis or ABAP development team for further investigation.