Compiler Error CS0037

Cannot convert null to 'type' because it is a non-nullable value type

The compiler cannot assign null to a value type; null can only be assigned to a reference type or to a Nullable type. struct is a value type. For more information, see Nullable Types (C# Programming Guide).

The following sample generates CS0037:

// CS0037.cs
public struct s
{
}

class a
{
   public static void Main()
   {
      int i = null;   // CS0037
      s ss = null;    // CS0037
   }
}