Compiler Error CS0577

The Conditional attribute is not valid on 'function' because it is a constructor, destructor, operator, or explicit interface implementation

Conditional cannot be applied to the specified methods.

For example, you cannot use some attributes on an explicit interface definition. The following sample generates CS0577:

// CS0577.cs
// compile with: /target:library
interface I
   void m();

public class MyClass : I
   [System.Diagnostics.Conditional("a")]   // CS0577
   void I.m() {}