C++ runtime library error r6025 pure virtual function call

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C#

WPF

hi I have a WPF application and a form app user control that have adobe pdf reader
I using windowshost to open pdf in wpf.
everything in opening and playing audio in pdf file is OK
closing wpf windows that contains pdfveiwer have no errors
but when application get closed this error appear
c++ runtime library error r6025 pure virtual function call

What I have tried:

// Create the interop host control.
System.Windows.Forms.Integration.WindowsFormsHost host =
new System.Windows.Forms.Integration.WindowsFormsHost();
host.Child = pdfViewer1;
// Add the interop host control to the Grid
this.GridPdf.Children.Add(host);


//in Windows Closed Event
pdfViewer1.PdfFilePath = "";
pdfViewer1.Dispose();
this.GridPdf.Children.Remove(host);