This must be a bug in C# when using user control DLL and class library DLL

[Tony Johansson]

Hello!

I have one solution file that consist of three project.
One project that build the exe file. called A
One project that build a user control dll called B
One project that build a class library dll called C

In the constructor for this user control is a call to a method in the class
library.
public (){

InitializeComponent();

Last.Last last = new Last.Last();

last.foo();

}

In the exe file c-tor I have a call to a method in the class library.
So in the project reference settings for the exe file I have a project
reference to the class library and to
the windows control because I can drag the windows control from the toolbox
to a form in the project that build the exe file.

Now to my problem if I now rebuild the project only for the class library
and then try to drag the windows control to a form I get the following error
"An exception occured while trying to create an instance of Middle.Middle.
The execption was "?"."

But if I rebuild the windows control instead then I can drag the windows
control from the toolbox to a form in the project that build the exe file.

My first question why do I get this error.
My second question is what is the recommended setting for copy local that
exist on each project. It it to have true or false.

My third question is what requirement is it about the version that each dll
have. I mean when an exe file will call a dll or when a dll will call
another dll.

//Tony
I just wonder what is the requirement about the dll and its version on the
dll

I noticed that when I get error