What issues might I have in opening .NET 2.0 Projects in Visual Studio 2010?

Question

The small software team I work on recently got approved to upgrade to Visual Studio 2010 (we're currently using VS 2005). We have several ASP.NET 2.0 and WinForms (in .NET 2.0) projects in production.

I've been tasked with downloading VS 2010 and seeing how well it plays with our current projects. What issues should I be aware of when targeting older applications in VS 2010? If I open a VS 2005 project in VS 2010, will it still place nicely when my teammate goes back to open the project in VS 2005? Will we have to upgrade projects to work in VS 2010 (assuming the projects themselves aren't upgraded to .NET 4)? Can I use VS 2010 to edit legacy VB6 apps (just kidding)?

I'm excited to work with the newest software, but we're concerned about running into development snags on production applications that are already working just fine.

NOTE: I started a bounty in hopes of getting a more detailed answer to this question. Perhaps the answer really is as simple as those already provided, but I'm interested in more feedback regarding our options to transition from using VS 2005 to VS 2010.

Answer 1

You will certainly have to "upgrade" your project and solution files. This makes it difficult to have a mixed team on VS2k5 and VS2k10. The solution file and project files can no longer be opened in previous versions of visual studio after they've been upgraded.

You can get around this by having two copies of each of your solution and project files, but this is clumsy as obviously changes made to one will need to be copied manually to the other.

In addition, it seems that you won't be able to use any pre-.NET 4.0 nit test projects with VS2010. If you use MSTest to test pre-4.0 applications, that's an argument against moving to VS2k10 at all. You'd need to port your app to 4.0, or port your tests to e.g. NUnit.

There were some bugs in Beta 1 regarding the layout of the solution explorer. All of the ones listed on Connect are "fixed", but it's worth being aware that the upgrade wizard might make mistakes that you'll have to fix manually. Assuming your whole team is migrating to vs2k10 that kind of issue isn't a big deal as it's pretty obvious if something goes wrong, pretty easy to fix, and only happens once.

Answer 2

Our company never had any problems moving our ASP.NET projects from 2005 to 2008 and so I wouldn't foresee any particular problems (though we haven't moved to 2010 yet, so bare this in mind). Most people I know have had the same experience. As others have mentioned, there is an automatic upgrade wizard that take care of upgrades for you, and it's always worked flawlessly for all projects I've upgraded . However, you won't be able to open the newly upgraded solution file in previous versions of Visual Studio (so back these up first if you want to retain them - though it may be possible to hack the .sln files to go back if really necessary).

You can, however, have multiple versions of Visual Studio installed at once (but remember that only one version can have default file extensions associated with it and this will likely be latest version you install). Incidentally, if you are interested in why you can't open older solutions in new version without conversion, then read this official VS Blog entry.

Remember, though, that Visual Studio 2010 allows you to target any previous version of the .NET Framework. So, if for some reason you wish your projects to stay at .NET 2.0 you can do so. However, in reality there is no real advantage I can see in this. Personally I think you just need to bite the bullet and upgrade everything - it's not really practical for people to use different versions for the same solutions.