We have a vs2005 solution including 2 websites. We converted the solution to vs2010 and changed all settings in IIS and in the config file to use framework 4.0. We removed the old assembly references in webconfig file and added references to the new versions of the assemblies. And here the problem comes. When we add a refererence to System.Design assembly in the webconfig file the website does not build. The build via msbuild.exe results in the following error:
ASPNETCOMPILER : error ASPPARSE: Object reference not set to an instance of an object. [d:\DevSites\SolutionFolder\WebSite.metaproj]
Does anyone have any suggestions why this happens ?