I also faced this issue. the root cause for my problem is as below.
1) I referenced below in my code. but i haven't added the library( System.Xml.Serialization.xml). Add Reference and select System.Xml.Serialization.xml to include the dll.
System.Xml.Serialization
2) I use an usercontrol called FileList.xaml in the mainwindow
FileList.xaml
<AM:time2str x:Key="time2str"/>
But i didnt add the class which inherits from IMultiValueConverter
MainWindow.xaml.cs(I missed the following code)
public class time2str : IMultiValueConverter
{
public object Convert(object[] values, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
********************
}
public object[] ConvertBack(object value, System.Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new System.NotImplementedException();
}
}