How To Fix WS301 - Function & not defined

SAP Error Message - Details

• Message type: E = Error

• Message class: WS - Supplier Billing Document

• Message number: 301

• Message text: Function & not defined

What causes this issue?

You requested function &V1&. However, this is not defined.

System Response

Function &V1& could not be executed.

How to fix this error?

If you did not request function &V1& manually, the message is usually
due to a system error. If necessary, contact your system administrator.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message WS301 - Function & not defined ?

  SAP Error Message:
  
  WS301 Function & not defined
  
  Cause:
  This error occurs when a function code (also called a function key or function module) that is expected or called in a screen or program is not defined or not recognized by the system. In SAP, function codes are used to identify user actions (like pressing a button or menu item) and trigger corresponding processing logic. If the program or screen expects a function code that has not been declared or assigned, the system raises this error.
  Common scenarios causing this error:  
  
  The function code used in the program or screen is misspelled or incorrect.  
  The function code is not declared in the screen's flow logic (e.g., in the PAI module).  
  The function code is missing in the GUI status (menu or toolbar) assigned to the screen.  
  Custom development or enhancement calls a function code that is not defined in the current context.
  
  
  Solution:
  
  
  Check the Function Code in the Program/Screen:  
  
  Verify the function code mentioned in the error message (the & will be replaced by the actual function code in the real message).  
  Ensure it is correctly spelled and matches the function code defined in the screen or GUI status.
  
  
  
  Define the Function Code in the Screen Flow Logic:  
  
  Go to the screen painter (transaction SE51) for the screen where the error occurs.  
  In the PAI (Process After Input) module, check if the function code is handled in the MODULE statements.  
  If missing, add the necessary logic to handle the function code.
  
  
  
  Check the GUI Status:  
  
  Use transaction SE41 or SE80 to check the GUI status assigned to the screen.  
  Verify that the function code is assigned to a menu item, pushbutton, or toolbar button.  
  If missing, add the function code to the GUI status.
  
  
  
  Check Custom Enhancements or User Exits:  
  
  If the error occurs after a custom enhancement or modification, verify that the function code used in the enhancement is properly defined and handled.
  
  
  
  Transport and System Consistency:  
  
  Sometimes, the function code might be defined in a development system but missing in the target system due to transport issues.  
  Ensure all relevant objects (screens, GUI statuses, programs) are properly transported.
  
  
  
  
  Related Information:
  
  
  Function Codes in SAP:
  
  Function codes are identifiers for user actions, typically 1-4 characters long, used in screen programming to control flow.
  
  
  Screen Flow Logic:
  
  The PAI module processes user input and reacts based on the function code received.
  
  
  Transactions to Use:  
  
  SE51 (Screen Painter) to check screen flow logic.  
  SE41 (Menu Painter) or SE80 (Object Navigator) to check GUI statuses.  
  SE38 or SE80 to check the ABAP program logic.
  
  
  
  SAP Notes and Documentation:
  
  Check SAP Notes or the SAP Help Portal for any known issues related to the specific function code or module.
  
  
  
  Summary:
  
  The WS301 error indicates that a function code expected by the program or screen is not defined or recognized. To fix it, verify and define the function code in the screen flow logic and GUI status, and ensure consistency across systems.