RadUpload has been replaced by RadAsyncUpload, Telerik’s next-generation ASP.NET upload component. If you are considering Telerik’s Upload control for new development, check out the documentation of RadAsyncUpload or the control’s product page. If you are already using RadUpload in your projects, you may be interested in reading how easy the transition to RadAsyncUpload is and how you can benefit from it in this blog post. The official support for RadUpload has been discontinued in June 2013 (Q2’13), although it is still be available in the suite. We deeply believe that RadAsyncUpload can better serve your upload needs and we kindly ask you to transition to it to make sure you take advantage of its support and the new features we constantly add to it.
If you modify the master page ID during the OnInit event, the RadUpload's UploadedFiles collection is empty when the control is placed in a content page.
Use the RadUploadContext.Current.UploadedFiles to access all the uploaded files.
To use the RadUploadContext.Current property you need to register the RadUploadHttpModule in the web.config.