How To Fix APPLG403 - MUX: There is no multiplexer to process the graphics event

SAP Error Message - Details

• Message type: E = Error

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

• Message number: 403

• Message text: MUX: There is no multiplexer to process the graphics event

What causes this issue?

There was a graphical event in the multiplexer callback process. The
callback process cannot deal with the event because no multiplexer
instance exists.

How to fix this error?

Correct the call method.
The reference variable GMUX in the interface file must be filled ONCE
by the application (CREATE MIX).
If you want to process the event yourself in PAI, then you must not
register the MUX callback for this event (see graphics proxy's method
GP_REGEVENT).
Also make sure that the method CL_GFW_MUX=>ACTIVATE
is called in PBO.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message APPLG403 - MUX: There is no multiplexer to process the graphics event ?

  The SAP error message APPLG403 MUX: There is no multiplexer to process the graphics event typically occurs in the context of SAP GUI or when using SAP applications that involve graphical user interfaces. This error indicates that the system is unable to find a multiplexer (MUX) to handle the graphics event, which can be due to several reasons.
  Causes:
  
  Missing or Incorrect Configuration: The multiplexer may not be properly configured or may be missing from the system.
  Network Issues: There could be network connectivity problems that prevent the SAP GUI from communicating with the application server.
  SAP GUI Version: The version of the SAP GUI being used may not be compatible with the backend system.
  Server Issues: The application server may be down or experiencing issues that prevent it from processing requests.
  User Authorization: The user may not have the necessary authorizations to access the graphics functionalities.
  
  Solutions:
  
  Check Configuration: Ensure that the multiplexer is correctly configured in the SAP system. This may involve checking the instance profile and ensuring that the MUX is running.
  Restart the MUX: If the multiplexer is running but not responding, restarting it may resolve the issue.
  Network Troubleshooting: Verify network connectivity between the SAP GUI and the application server. Check for firewalls or other network configurations that may be blocking communication.
  Update SAP GUI: Ensure that you are using a compatible version of the SAP GUI. If necessary, update to the latest version.
  Check Server Status: Verify that the application server is up and running. You can check the status of the server using transaction codes like SM51 or SM66.
  User Authorizations: Check the user’s authorizations to ensure they have the necessary permissions to access the graphics functionalities.
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any known issues or patches related to this error. SAP Notes can provide specific guidance based on the version of SAP you are using.
  SAP Community: Engage with the SAP Community forums to see if other users have encountered similar issues and what solutions they found effective.
  Logs and Traces: Review system logs (transaction SM21) and traces (transaction ST01) for any additional error messages or warnings that could provide more context about the issue.
  
  If the problem persists after trying the above solutions, it may be necessary to contact SAP support for further assistance.