I'm opening a solution that was apparently built on Visual Studio 2003 (not sure, I don't know anything about it) and trying to migrate to 2010. When trying to migrate I get the message:
the application for project '' is not installed make sure the application for the project type (.csproj) is installed.
If I open each one of the single projects of the solution they migrate fine but not the solution itself.
If your projects individually migrate fine, then create a new blank visual studio 2010 solution, and add new projects individually (right click on solution->add->existing project)
But I'm not sure that your projects will load fine individually. There are project types that require some additional software to be installed in order to be supported. The most frequent problems I face are old projects built with old versions of asp.net mvc (1 or 2) and I have asp.net mvc 3 installed...or really old projects built with asp.net ajax...In those cases, you have to install that additional software and then import project, or find a tool to upgrade that project type to a newer version.