Compiler Error CS0061
Inconsistent accessibility: base interface 'interface 1' is less accessible than interface 'interface 2'
A public construct must return a publicly accessible object.
Interface accessibility cannot be narrowed in a derived interface. For more information, see Interfaces (C# Programming Guide) and Access Modifiers (C# Programming Guide).
The following sample generates CS0061.
// CS0061.cs
// compile with: /target:library
internal interface A {}
public interface AA : A {} // CS0061
// OK
public interface B {}
internal interface BB : B {}
internal interface C {}
internal interface CC : C {}