Running .NET 2.0 & 3.5 web sites in IIS 7

Question

I heard there is a problem or a certain way you must setup IIS in order to run both .NET 2.0 and .NET 3.5 sites concurrently?

We don't see a .NET 3.5 option in the dropdown when configuring the site framework.

Answer 1

If it's set to run .NET 2.0, it will run .NET 3.5. There is no separate setting for .NET 3.5.

Answer 2

.Net 3.5 is just an extension of .Net 2.0. Choose .Net 2.0 (and make sure you have 3.5 installed on the server.)

.Net 3.5 Websites will run under the .Net 2.0 setting on IIS.

I use IIS7 at home, and I have no problem.

Answer 3

There are two versions of the CLR, which actually runs .NET code: 1.1 and 2.0 (with a new version still in beta).

The framework, the base class libraries that everyone uses, are updated more regularly. We're up to 3.5 sp1 now.

Compilers add a little more complexity as well... When 3.0 came out there were some updates to the C# compiler that added lambdas, automatic properties and other candy to the language...

So when you're looking at running code, think in terms of CLR versions. When you're looking at developing code, think of the version of the BCL you wish to target. Compiler versions are tied to the IDE, so you'll probably never have to think about that.

Answer 4

If you want to read a longer explanation of this, check out How to set an IIS Application or AppPool to use ASP.NET 3.5 rather than 2.0 by Scott Hanselman.