PDF document fails to load in .Net webbrowser after upgrade to Windows 10 20H2

When loading a PDF-document into a .NET webbrowser (when using Acrobat Reader DC in combination with Windows 10 20H2), the webbrowser control does not load the document. The control remains grey and no error is generated.  In Windows 10 versions prior to 20H2 the .pdf file is displayed as expected. 

The code to reproduce the problem is as follows:

&SCOPED-DEFINE PDFFile C:\Temp\openedge-install.pdf

DEFINE VARIABLE hWin         AS HANDLE                           NO-UNDO.
DEFINE VARIABLE MainForm     AS Progress.Windows.Form            NO-UNDO.
DEFINE VARIABLE oWebBrowser  AS System.Windows.Forms.WebBrowser  NO-UNDO.
DEFINE VARIABLE WinContainer AS Progress.Windows.WindowContainer NO-UNDO.

DEFINE FRAME f1.

ASSIGN FRAME f1:WIDTH-PIXELS  = SESSION:WORK-AREA-WIDTH-PIXELS / 2
       FRAME f1:HEIGHT-PIXELS = SESSION:WORK-AREA-HEIGHT-PIXELS / 2
       .

CREATE WINDOW hWin 
  ASSIGN WIDTH  = FRAME f1:WIDTH
         HEIGHT = FRAME f1:HEIGHT.
   
ASSIGN FRAME f1:PARENT = hWin.

/* Create the .NET form. */
ASSIGN MainForm            = NEW Progress.Windows.Form()
       MainForm:Text       = ".NET Webbrowser-control":U
       MainForm:ClientSize = NEW System.Drawing.Size(hwin:WIDTH-PIXELS, hwin:HEIGHT-PIXELS)  .

MainForm:FormClosed:Subscribe("Window_FormClosed":U).
MainForm:Show().

/* Create the .NET webbrowser */
ASSIGN oWebBrowser          = NEW System.Windows.Forms.WebBrowser()
       oWebBrowser:Location = NEW System.Drawing.Point(0, 0)
       oWebBrowser:Name     = "WebBrowser":U
       oWebBrowser:Width    = hwin:WIDTH-PIXELS
       oWebBrowser:Height   = hwin:HEIGHT-PIXELS.
       
MainForm:Controls:Add(oWebBrowser).

/* Create the WindowContainer, embedding the window into it. */
ASSIGN WinContainer                = NEW Progress.Windows.WindowContainer()
       WinContainer:Size           = NEW System.Drawing.Size(hWin:WIDTH-PIXELS, hWin:HEIGHT-PIXELS)
       WinContainer:EmbeddedWindow = hWin
       WinContainer:Parent         = MainForm.
       
WinContainer:Show().

IF SEARCH("{&PDFFile}":U) <> ? THEN
  DO:
    oWebBrowser:Navigate("{&PDFFile}":U). 
  END.
ELSE
  DO:
    MESSAGE "File ":U + "{&PDFFile}":U + " not found.":U
     VIEW-AS ALERT-BOX ERROR BUTTONS OK.
  END.

/* Now make the window visible. It will be realized inside the WindowContainer. */
ASSIGN hWin:VISIBLE = TRUE.

ENABLE ALL WITH FRAME f1.

WAIT-FOR System.Windows.Forms.Application:Run(MainForm).

/* Delete the embedded window after the main form closes. */
PROCEDURE Window_FormClosed:

  DEFINE INPUT PARAMETER sender AS System.Object.
  DEFINE INPUT PARAMETER e AS System.EventArgs.

  DELETE WIDGET hWin.
END PROCEDURE.

In Windows 10 versions prior to 20H2 this code displays the pdf file as expected.

 

The problem happens when using the Adobe Acrobat DC reader and the Windows 10 machine has been upgraded to Windows 10 20H2 or later (e.g. Windows 10 21H1).

This is a Microsoft problem introduced with the Windows 10 upgrade.  The problem is fixed in a later update:

Security Update for Microsoft Windows (KB5004945)

Install the Microsoft Windows KB5004945 update as described here:

https://support.microsoft.com/en-us/topic/july-6-2021-kb5004945-os-builds-19041-1083-19042-1083-and-19043-1083-out-of-band-44b34928-0a71-4473-aa22-ecf3b83eed0e

 

• For the time being disable the "Windows Update" service in Windows services, on Windows 10 machines that haven't yet been upgraded to 20H2 or later.
• Revert the Windows 10 machine to the version prior to the upgrade.  
• Use and alternative pdf reader such as 'Foxit' - https://www.foxit.com/pdf-reader/