Steps to Investigate Cause of Web.Config Duplicate Section
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        Published on 2010-03-19T06:14:57Z
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Symptoms
In IIS Dot Net 2.0 Integrated app pool: double clicking to view any web.config section results in a the following error dialog. "There was an error while performing this operation.... Fielname... web.config... Error: There is a duplicate..."
Browsing to the URL displays: "Http 500.19" internal server error.. There is a duplicate... 'system.web.extensions/scripting/scriptResourceHandler' section defined...."
Running the app from VS 2008 an "Unable to start debugging on the web server..." dialog is displayed.
Things Tried
- Looked at other application directories on same IIS server. No problem view web.config contents or serving up the app.
 - Removed and re-added the application in IIS.
 - Checked out a new version of the source code.
 - Reverted to prior versions of the web.config file.
 - Looked for web.config files that might have duplicate sections in:
- Inetpub root.
 - "C:\Windows\Microsoft.NET\Framework\v2.0.50727\CONFIG\machine.config"
 - The "Views" subfolder of the ASP.Net MVC app.
 
 - Checked out source code to another dev machine. Setup IIS 7 app folder. No problem with Web.config.
 
Question
- If the reason for this error is another web.config file where else should I look?
 - Are there other reasons for these symptoms?
 
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