Can open MVC4 solution in VS2010, but not in VS2012

Question

Looked through some similar questions, could not find one that fits my case.

I have a solution that I created some time ago in VS 2010 (maybe originally in MVC2), and eventually upgraded to MVC4. The solution works properly when opened with VS 2010, builds and runs - everything as expected.

To confirm that I use MVC4, I checked the properties of my System.Web.Mvc.dll. It appears to be 4.0.0.0

From this I assume that I have MVC4 successfully installed on the machine.

However, when I try to open the solution with VS 2012 I get the following infamous error

Full text:

Unsupported This version of Visual Studio does not have the following project types installed or does not support them. You can still open these projects in the version of Visual Studio in which they were originally created. - Recipes, "C:\ ... Copy\Recipes\Recipes.csproj"

I can also create a new MVC4 project using VS 2012, so I'm assuming I don't lack any tools VS 2012 needs.

What else could be the problem?

Answer 1

There's probably an entry in the <ProjectTypeGuids> element of the .csproj file that VS2012 doesn't recognize. I have a vague recollection there was some tooling identifier change but I can't recall specifically.

My suggestion would be to create a new project from scratch and then compare the <ProjectTypeGuids> elements in each .csproj file to try to figure out which one from the VS2010 project it doesn't like in VS2012. It's likely going to require some trial-and-error tweaking of the list so make a backup of the file first so you don't get yourself into a situation where you can't open it at all.

If you don't want to take that approach another option would be to create a new empty project and then import the individual files from the old project into the new, but that could obviously be quite time-consuming if it's a large project.