A customer of mine was doing an upgrade of one of their Tax applications recently. The new application needed .Net v4.0 framework to be installed. The client did everything the application vendor instructed them to do but could not make the application work. He asked me to take a “quick look” at it.
I checked out the application vendors instruction first up and found that the client had done things to the letter. I then thought about the error message being recieved and realised that this was the first application on this server that would use the new .Net v4.0 framework.
I opened up IIS Manager on the server and then drilled into the ISAPI and CGI Restrictions area and found that the ASP.NET v4.0 entries were set to Not Allowed. It was easy to change this and then the site work as per the vendor described. It would have been great for the vendor to include this in their instructions for the client though – would have saved a lot of time!