Sys.WebForms.PageRequestManager error

While creating a new .Net 2.0 project I encountered something that had never happened to me when creating other ASP.Net web applications.

I had this new ASP.Net web application and I put in a script manager in the Master Page and an update panel in one of the content pages. When running this simple setup I got an error that had never happened before

Sys.WebForms.PageRequestManager._initialize Microsoft JScript runtime error: 'Sys' is undefined

This left me a bit confused but a bit of search on the web and I realized that there were some key values missing from the web.config.

Other projects that I had created were taken as AJAX enabled template projects and hence never posed any issue. The solution was to create a new ASP.Net AJAX enabled web application and then copy-paste the relevant sections from the new project in your web.config.