After deploying my new upgrade of Umbraco 4.7 to my production server an error occured when trying to logon the backend of Umbraco.
The logon progress bar displays and displays and displays but nothing happens. After exploring with firebug i’ve discovered the error in DepencyHandler.axd
After some searching I discovered that when you set compilation debug to true within web.config the problem is solved. This seems to disable Client Dependency Javascript in Umbraco.
Ofcourse this is NOT the solution on production servers.
After emptying the App_Data/ClientDependency folder and refreshing the back-end with F5 and it all worked again.