asp.net - Problem: System.Configuration.ConfigurationManager throwing exception -

I'm having this strange case, the first time the page gets loaded, it gets all right, but as soon as I Clicking on any link that makes any Ajax request, after that, I get this error when I try to read the configuration.

"System.configuration.ConfigurationManager.ConnectionStrings" has a type of exception "System.Web.HttpException"

I asp.net mvc 1.0 please help please in advance.

The problem was coming from an AJAX request whose route was in the data with the example example www.domain.com/account/index/%20routedata parameter. In this case, in Firebug 404 error was not found, while debugging on machine The Sm, it was throwing specified exceptions above.