Xamarin: No resource identifier found for attribute ‘?’

Have a look to the below 2 links https://stackoverflow.com/questions/30543993/navigationview-throwing-error-no-resource-identifier-found-for-attribute-menu https://stackoverflow.com/questions/30543993/navigationview-throwing-error-no-resource-identifier-found-for-attribute-menu

yes i did

Have you tried rebuild the project or restarting the visual studio