There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined

"There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined"

You are .NET developer and has this problem or error message while deploying your compiled apps using MS Visual Studio 2008 and try to deploy on IIS 7 or 8? Running Windows 8 Pro?

After commenting a lot in your web.config file does not help. These what you should do. It's works for me and hope it work for you as well.

I'm running Windows 8 Pro with IIS version 8.

 

Error message on my screen.

Config Error   There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined
Config File   \\?\C:\inetpub\wwwroot\admin_permata\web.config

"<section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions,......"

What should I do?
Google around and change my PC config.... it's really messy. Don't do it. You will forget what you have changed. It's just too many steps...

What I did!
In you PC control panel look for this. Turn Windows features on or off

Look for World Wide Web Services > Application Development Features

Enable it all. My case I did not use CGI. Just uncheck it. Click [OK] and get it installed.

You should have this on your IIS Application Pool.
Go to your IIS Manager. Select your web site and click on "Advanced Setting"

Change it from DefaultAppPool to Classic .NET AppPool

DONE!

Your app should run normally!