In some cases you may end up with the following exception when working with RadControls for ASP.NET Ajax:

"Script controls may not be registered after PreRender."

The explanation of this error is simple - some UI control implementing the IScriptControl interface (e.g. any control from the RadControls for ASP.NET Ajax suite) is stored in the Session, Application or Cache and then is added in some live controls collection. Here is an...