Installing .NET 3.5 on a server with .NET 2.0 applications

Question

I would like to upgrade my web projects on an IIS 5 server from .NET 2.0 to .NET 3.5. These web applications live on a server with other web applications that will not be upgraded to .NET 3.5. The server administrator is reluctant to install .NET 3.5 because he is afraid it will break the applications on that machine that are running 2.0 and 1.1.

As far as I know this WON'T be a problem since .NET 3.5 is an addition to 2.0 more than it is a new Framework. I would like the communities help gathering evidence to show him that their concerns are moot and it won't hurt the other applications.

Thanks in advance.

Answer 1

Hi,

It won't have any problem and you will be able to run your 2.0 and 3.5 application using the same server. This is because the code base for both of the frameworks is the same.

Answer 2

I've upgraded a couple servers from .net 1.1 to 2.0 & 3.5, there havent been any problems.

Answer 3

If you have .NET 2 SP1 you shouldn't have a problem.

To be exact .NET 3 & 3.5 are built on top of .NET 2.0 SP 1, we had a problem deploying 3.5 onto a server which only had .NET 2 (not SP1) and it caused the apps on there to break. The reason is your core framework assemblies in .NET 2 are upgraded and have new version numbers which the app wasn't compiled against.

Answer 4

Walk the server administrator through the content of the redistributable for 3.5. It adds a lot of new dlls it doesn't update anything in the 2.0.x directory. You might want to show him how the apps targeting 3.5 are still using System.dll etc from the 2.0.x framework directory.

Answer 5

Both frameworks can run concurrently. In fact, that is the default behavior.

One caveat though, make sure that you don't use the same application pool for apps using different versions of the framework. Otherwise you will get "Server Application Unavailable" errors. Use a different app pool for each set of applications.

Answer 6

Installing 3.5 will modify your .NET 2.0 web.config file and a few others.

This certainly breaks at least 1 application I use. Uninstalling 3.5 will revert the files and fixes the issue.