How To Fix WS301 - Function & not defined

WS301 - Overview

• 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.

WS301 - Details

• 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