2900689 - Logon button does not work using SAPGUI for HTML or Web Dynpro ABAP application

• When trying to launch SAPGUI for HTML (Webgui) tile from Fiori Launchpad (FLP) unable to proceed into the transaction from FLP.
• SAPGUI for HTML (WebGUI) service is activated, testing the service direct, after prompt to enter user and password and hit Logon (enter), it also does not go any further. It hangs on the logon screen. 
• Using e.g. Web Dynpro ABAP application after entering the logon credentials and pressing the 'Logon' button no action is triggered.
• Network trace shows 403 (or e.g. 404) error for systemloginjs ICF node.
• LTMC not working. e.g. browser page shows error message: "This site is not secure" "Your PC doesn't trust this website's security certificate."

Using HTTPWatch the following 403 (or it can also be a 404) error appears for the ICF service "systemloginjs":

• WEBGUI / SAP GUI for HTML
• Web Dynpro ABAP
• SAP NetWeaver
• ABAP PLATFORM - Application Server ABAP

WDA, Web Dynpro ABAP, Web Dynpro, WEBGUI, Webgui, Logon, logon screen, button, logon button, 403, 404, systemloginjs, SICF, service, inactive, triggered, not work, nw07.js, SAP GUI for HTML, SAPGUI for HTML, SAP GUI, GUI, UI, DLG_FLAGS_INVALID_CA , KBA , BC-MID-ICF-LGN , ICF System Login , BC-FES-WGU , SAP GUI for HTML , BC-FES-ITS , SAP Internet Transaction Server , BC-WD-ABA , Web Dynpro ABAP , Problem