How To Fix APPLG401 - MUX: Win ID already exists; check GP's call method

APPLG401 - Overview

• Message type: E = Error

• Message class: APPLG - Application Graphics Messages (Graphic Proxy Framework)

• Message number: 401

• Message text: MUX: Win ID already exists; check GP's call method

What causes this issue?

A graphics proxy is using a WIN ID that already exists in the
multiplexer for its logon.

How to fix this error?

Check the implementation or the graphics proxy's call method.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message APPLG401 - MUX: Win ID already exists; check GP's call method ?

  The SAP error message APPLG401 MUX: Win ID already exists; check GP's call method typically occurs in the context of SAP GUI or when using SAP's graphical user interface. This error indicates that there is an issue with the window ID (Win ID) being used in the application, which is likely due to a conflict where the same window ID is being reused or not properly managed.
  Causes:
  
  Duplicate Window ID: The error suggests that a window with the same ID is already open or being referenced, leading to a conflict.
  Improper Call Method: The method used to call the graphical user interface (GUI) might not be appropriate, leading to issues in window management.
  Session Management Issues: If multiple sessions are open or if there are issues with how sessions are being handled, it can lead to this error.
  Custom Code or Add-ons: If there are custom developments or third-party add-ons that manipulate GUI elements,