Due to a breaking change in DNN 5.3.0.0, installing the RadControls
modules will result in a server exception. To fix it, please, replace the
following two files in the following two locations
~\Website\App_Code\TelerikWebUI\RadEditorProvider.vb
~\Website\DesktopModules\TelerikWebUI\RadUpload\RadUpload.ascx.vb
with the attached ones to this sticky note.
Here is an update from DotNetNuke for the next release 5.3.1 in which the problem will be fixed:
DotNetNuke 5.3.1 Version now entering QA.
Best regards,
The Telerik team