Upgrade your ASP.NET MVC project from Visual Studio 2008 to 2010

I currently have a couple of projects going on. Some for clients, and then I have some ideas and experiments for myself, so that I can play around with NHibernate, LINQ to Entities, ASP.NET 4.0 and Visual Studio 2010.

I started one of my projects in Visual Studio 2008. Recently, I went to “The best of PDC 2009 with Scott Guthrie” here in Denmark. That was when I decided to upgrade some of my projects, so I could take full advantage of the upgrade from both Visual Studio, but also .NET 4.0. So I did. Or, so I thought. It all seemed straightforward, but when i opened the project in Visual Studio 2010, it converted with errors. The error I was getting was:

• The project file ‘<project file path>’ cannot be opened. The project type is not supported by this installation.

First, I was like… Did I miss something in the installation? But no, I didn’t. I started Googling around and found this solution:

• Open up the project file file in notepad (or your favorite text editor) and replace the entire <ProjectTypeGuids> tag with the following tag:
• <ProjectTypeGuids>{349c5851-65df-11da-9384-00065b846f21};{fae04ec0-301f-11d3-bf4b-00c04f79efbc}</ProjectTypeGuids>.

It works! But why, I don’t know. That’s why I just e-mailed Scott Guthrie, hoping he could shed some light over this. He actually replied me and told another guy, Eilon Lipton, to help me with the problem.

I will, of course, update this post when I have a solution – or at least a decent explanation.