.NET: Is it possible to install .NET frameworks 2.0 and 3.5 after installing .NET 4.0?

Question

Recently, when I run my visual studio 2010 in order to open my own vb.net project , I get the following message from vs:

"The VB.NET project project1 is targeting ".NETFramework, Version 2.0", which is not installed on this machine. You must download this framework, as well as .NET framework3.5, in order to open and build this project....."

I should mention that it was ok before and I could open my project and build it via VS2010. What can I do? What is your suggestion?

Thanks a lot.

Answer 1

Did you uninstall the previous .NET framework version when you installed .NET4?

You can change the project to compile with .NET4 and it should be all fine, or install the older framework versions (again).

You will find no problem in installing these older frameworks over the top...With one exception (that I am aware of). After installing both .NET3.5 framework, you will need to run this command:

C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i

This is because the older installers remove ASP.NET4.0 from IIS (which is correct behavior).

Otherwise it's no problem and I have done it to machines several times (happens often with Win2k8 servers since they only come with .NET3.0 and the .NET3.5 install is on the server and not a download package, so people neglect to install it if using .NET 3.5 instead).

But most likely you just need to upgrade your project for .Net4 in the project settings window.

Answer 2

Is it possible installing .net frameworks 2.0 and 3.5 after installing .net 4.0?

Yes.

I should mention that it was ok before and I could open my project and build it via VS2010.

Okay. Did you uninstall the .NET Frameworks 2.0 and 3.5 subsequent to that?

What can I do? what is your suggestion?

Install them.