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

See more:

ASP.NET

VS2010

IIS7.5

, +

I’m creating a custom asp Form using visual studio 2010 on sharepoint server 2010, and when I try to debug it I face this error message

"Unable to start debugging on the web server. See help for common configuration errors. Running the web page outside of the debugger may provide further information.
Make sure the server is operating correctly. Verify there are no syntax errors in web.config by doing Debug.Start without debugging. You may also want to refer to the ASP.NET and ATL server debugging topic in the online documentation."

And when I try to debug.start without debugging this how the web page be , its not working and show this error

Server Error


Internet Information Services 7.5



Error Summary
HTTP Error 500.19 - Internal Server Error

The requested page cannot be accessed because the related configuration data for the page is invalid.


Detailed Error Information



Module

IIS Web Core



Notification

Unknown



Handler

Not yet determined



Error Code

0x800700b7



Config Error

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



Config File

\\?\C:\inetpub\wwwroot\wss\VirtualDirectories\80\web.config





Requested URL

http://localhost:80/_layouts/SimpleCopyFileForms/AssociationForm/Design_AssociationForm.aspx



Physical Path




Logon Method

Not yet determined



Logon User

Not yet determined




Config Source   24:       <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
   25:         <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication" />
   26:         <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">

My Platform is Windows server 2008 SP1, IIS 7.5 , Sharepoint Server 2010 , Visual Studio 2010
I checked if there’s a duplication in the web.config file between the application web.config and root web.config, but nothing ,, I also checked the App pool for my aspx page ,, but nothing also.
And when I create normal asp page ( save it locally not on the SP server ) it works perfect !!
(hints :
- in the web.config file , debug = “true”
- “sharepoint – 80” application pool’s .net framework is version 2
- My aspx applications pool’s .net framework is version 4

Anyhelp?