Symptoms

  • In IIS 7 and Dot Net 2.0 Integrated app pool: double clicking to view any web.config section results in an error dialog like this:

"There was an error while performing this operation.... Filename... 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.

Infrastructure

  • Web server: IIS 7 running on Windows 7 x64
  • ASP.Net MVC2
  • Application pool: Dot Net 2.0 integrated
  • VS 2008

Things Tried

  • Checked to see if the problem was occurring in other IIS app directories on the same machine.
  • Removed and re-added the application in IIS.
  • Reverted to prior versions of the web.config file.
  • Checked out a last working version of the source code. Rebuilt the app, added a new app directory for it and tried to view web.config contents from IIS.
  • 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?
asp.net asp.net-mvc iis-7
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