Sometimes when setting up your ASP.Net site on IIS, you may find that normal HTML or ASP pages display OK, but all .aspx pages generate a 404 file not found error.

This usually happens when ASP.Net does not appear as a valid web service extension in IIS, or if it is not set to "Allowed".

To fix this:

• Start IIS Manager and click on Web Services Extensions in the navigation tree.
• If ASP.Net 2.0 is listed, check that it is set to "Allowed" (often it is set to "Prohibited" by default).
• If ASP.Net 2.0 is not listed, then you need to register it in IIS.
  • From the command prompt, execute "aspnet_regiis -i"
  • Now verify it appears in Web Service Extensions and is set to "Allowed" as above.