3806117 - WEBGUI in FLP sporadically shows "A back-end error has caused the application to terminate." (HTTP 400)

• Users are unexpectedly logged out from SAP Fiori Launchpad at irregular intervals during normal work.
• Error message: "A back-end error has caused the application to terminate. Error message returned: HTTP 400" 
• The behavior is sporadic and cannot be reproduced deliberately.
• The error might also occur when users switch between browser tabs or windows and then return to the original WEBGUI tab.
• The behavior might be observed across multiple browsers, including Microsoft Edge and Google Chrome. 
• No corresponding entries are found in SM21 or ST22. Checking /IWFND/ERROR_LOG and /IWBEP/ERROR_LOG may also yield no relevant entries.

"Image/data in this KBA is from SAP internal systems, sample data, or demo systems. Any resemblance to real data is purely coincidental."  

• SAP S/4HANA 
• SAP GUI for HTML (WEBGUI) embedded in SAP Fiori Launchpad (FLP)
  (Refer to the "Testing WEBGUI directly" part of the "See Also" section below for further details in this regard.)

3717969, 3727104, HTTP 400, intermittent, unexpected logout, session termination, Fiori Launchpad, Microsoft Edge browser, WebGUI, GUI for HTML, keep alive, ExtendSession, SAPWEBGUI, kernel upgrade, sporadic error, HAR trace, SM21, ST22, issue is not permanent, problem cannot be reproduced by will, issue occurs intermittently, Ein Backend-Fehler führte zum Abbruch der Anwendung. Fehlermeldung: HTTP 400, Failed to load resource: the server responded with a status of 400 , sap/bc/gui/sap/its/webgui/batch/json , Ping timeout occurred, no data received for 120 seconds , Google Chrome, Chrome 149, Chrome 153, multiple browsers, tab switching, ExtendSession, %_KEEPALIVE, keepalive regression, Kernel 793, PL410, data loss, unsaved work, Ping timeout, WebSocket, dev_icm, FLP session management, logoff service, MYSAPSSO2, ICMENOSESSION, session timeout, browser performance, tab suspension, A backend error caused an abort of the application, returning:, , KBA , BC-FES-WGU , SAP GUI for HTML , BC-ABA-SC , Dynpro and CUA engine , CA-FLP-FE-AI , Application iframe communication in FLP and Work Zone , CA-FLP-ABA , SAP Fiori Launchpad ABAP Services , BC-FES-ITS , SAP Internet Transaction Server , BC-MID-AC , ABAP Channels , BC-CST-IC , Internet Communication Manager , BC-CST-DP , Dispatcher, Task Handler , Problem