'method' : extern method has no implementation. Should be marked dllimport or sysnative
A method marked extern must also be marked with either the dllimport or sysnative attribute.
The following sample generates CS0626:
public class MyClass { static extern public void mf(); // CS0626 // try the following // [dllimport("mydll.dll")] static extern public void mf(); // or // [sysnative] static extern public void mf(); public static void Main() { } }