The type or namespace name 'X' could not be found (are you missing a using directive or an assembly reference?)

Question

I have a weird problem I just can't place.

I have a SP 2010 project which contains two sub-projects of type class library (FirstLib and SecondLib).

The project build fine, no errors whatsoever, but once I deploy to the server I get errors in VisualStudio's "Error List" window:

The type or namespace name 'X' could not be found (are you missing a using directive or an assembly reference?)

The type X is in FirstLib and is referenced from SecondLib. In the package manifest I specified that both be deployed to GAC and I can see they are there, but I still see that message, and I get it for every type in FirstLib that is used by SecondLib.

What's even weirder is that in the "Output" window I see this.

========== Build: 3 succeeded or up-to-date, 0 failed, 0 skipped ========== ========== Deploy: 1 succeeded, 0 failed, 0 skipped ==========

What could be the cause for this?

What should I check further?

Answer 1

I get this exact problem myself. I can't work it out either, but I have noticed that it will only occur when I have certain source code files open and active in Visual Studio (in your case it would be a code file from the SecondLib project), and it would only occur when trying to do a package or deploy action.

If you close the source files from SecondLib before doing a deploy the errors should go away.

Answer 2

I had the same problem. (Re-)Built successful but deployment to SharePoint and manually packaging (Visual Studio -> Pubish) failed. I solved the problem by switching "Copy-Local" to false in every project (about 15 Class Library projects and three SharePoint Projects).

I think the problem is the linking between each project so Visual Studio can not resolve the dependencies in the right way.

Answer 3

Make sure you've added other projects to main package. See http://www.sharemuch.com/2010/03/17/deploying-referenced-assemblies-with-your-vs2010-sharepoint-2010-wsp-solution/

Also you can open in Windows Exploerer - C:\Windows\Assembly and make sure your referenced dlls are deployed to GAC.