Xamarin.Forms 3.1 error

After updating the Xamarin.Forms 3.0 to Xamarin.Forms 3.1 when I used

        xmlns:android="clr-namespace:Xamarin.Forms.PlatformConfiguration.AndroidSpecific;assembly=Xamarin.Forms.Core"
                android:TabbedPage.ToolbarPlacement="Bottom"
            android:TabbedPage.BarItemColor="#666666"
            android:TabbedPage.BarSelectedItemColor="Black"

I am getting this error.
Unhandled Exception:

System.TypeLoadException: Could not resolve type with token 01000029 (from typeref, class/assembly Xamarin.Forms.Xaml.XamlResourceIdAttribute, Xamarin.Forms.Core, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null) occurred