The format of the uuid was not correct.' reason
A syntax error occurred because of an invalid uuid format.
The following sample generates CS0647:
using System.Runtime.InteropServices; [GuidAttribute("z")] // CS0647 // try the following line instead // [GuidAttribute("00000000-0000-0000-0000-000000000001")] class MyClass { public int this[int index] { get { return 0; } } public static void Main() { } }