ref:http://www.code101.com/Code101/DisplayArticle.aspx?cid=85
Problem
I got this Error message when I was trying to do a web set up for my ASP.NET Web Application. I get to this message in the output window during the compilation. Unfortunately the message shown does not contain any reason why this error occurred and how to resolve this. Error Message
Unable to build project output group 'Content Files from <ProjectName> (Active)’ Where <ProjectName> is the Name of ASP.NET project for which I am trying to create a setup.Cause
This Error occurs because some of the files referenced in your project are not present in the specified directory. While trying to build a set up, the Microsoft Installer (MSI) builder throws this error if it cannot find a physical file that is referenced in the project. So all the files referenced in the project should be present in the specified physical paths before you run the set up. In the following Solution explorer, some of the images like Branches.gif, CIP.gif etc... are not present in the specified path. If we try to build a set up for this project without excluding these files , the set up fails with the above error message.Solution
a)Remove all the referenced files in the project that are not present in the designated physical path. These files have a yellow icon displayed next to it in Solution explorer. Expand all your project related folders like Images, Docs, References etc. and exclude all the files with yellow icon next to it from the project.
b)Rebuild the Application and then Rebuild the Setup and Deployment Project.
c)You should be able to build the setup successfully now.