HTTP Error 404.3 - Not Found

Problem

You get this error when first displaying a page on Microsoft Vista running IIS 7.0:

HTTP Error 404.3 - Not Found

The page you are requesting cannot be served because of the extension configuration.

Solution

If the page is a script, add a handler. If the file should be downloaded, add a MIME map.

Microsoft Vista running IIS 7.0 issues errors that pages with aspx extensions are not being resolved.

Check the following link to see which features are enabled in Vista.

http://pcwizkid.wordpress.com/tip-12-windows-vista-features-slowing-you-down/

To get to the Vista feature set:

Control Panel->Programs and Features->Turn Windows Features On or Off

This will bring up the list of Vista component features that are available to be turned on or off. Note the settings under World Wide Web Services and Microsoft .Net Framework 3.0. Most of these features come turned off on new Vista installations and new Vista machines. Depending on the type of development or deployment, these may have to be enabled for IIS 7 to resolve and display aspx pages.

Additional details and suggestions

http://iweb.adefwebserver.com/Project/Blog/tabid/57/EntryID/34/Default.aspx

http://social.msdn.microsoft.com/Forums/en-US/wcf/thread/224f04bd-12e5-4988-a08c-038c66e0705c/