I am having DELL laptop with Windows 7 professional, IIS 7.5.

I have installed .Net framework 2.0, 3.5, 4.0.

Some of my old asp.net applications are built on framework 2.0 and 3.5. I tried configuring the application in IIS but it is not showing me framework settings. The only thing i can set is the application pool but it is showing only 4.0.

Anyhow, i configured the application for 4.0. When i try to access the application i am getting error message in the browser.

Software Genius Inc

When i try to execute it from Visual Studio 2008 i am getting the following error.

Software Genius Inc

Can anybody help me out resolve this issue.

2 Answers 2


For one thing, you should re-register .NET 2.0 and 3.5 for IIS (in the select box of the application pool settings the only choices will be 2.0 and 4.0 - and the non managed setting - because .NET 3.x is basically the "same" as 2.0 with quite a few libraries added, but 2.0 should definitely be there).

You can try

C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i -enable

or google "register .net 2.0 iis 7.5" or "aspnet_regiis" directly - this will give you a lot of information.

Secondly, your application is not running under 4.0 because the web.config is not configured properly (it says so in your error description). You have a duplicate section somewhere (it's too small to read for my eyes). Check this and make sure the web.config is valid.

  • Thanks Olaf for your quick reply. First thing, the applications which i am trying to execute on IIS 7.5 are already tested for IIS 6. I just ported it to IIS 7.5. Secondly, i tried registering the .Net 2.0, 3.5 as you given but didn't solve the problem.
    – IrfanRaza
    Mar 27, 2012 at 18:59
  • @IrfanRaza: did you try fixing the web.config as I described in my answer?
    – Olaf
    Mar 28, 2012 at 8:31
  • yes i did but still same issue.
    – IrfanRaza
    Mar 29, 2012 at 12:16
  • Can you post your web.config?
    – Olaf
    Mar 29, 2012 at 12:45

Try changing the application pool to run in classic mode instead if integrated, for the affected applications.

You should be able to run a web application with a .Net 2.0/3.5 configured web.config file in IIS 7.5 using this setting

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