Hello Sam Van,
The current version of the RadUpload for ASP.NET AJAX does not support uploading files with AJAX due to a limitation of the XmlHttpRequest component which is used in all AJAX frameworks for asynchronous calls to the application. However, we suggest a workaround that makes possible the use of the RadUpload control with AJAX. You can take a look at RadUpload's AJAX support
for more details. We have entered the issue in our feature requests list for future consideration and investigation.
Currently, RadUpload Prometheus works only in IIS7 Classic mode and Cassini. It does not support Integrated IIS7 mode. At the moment we are investigating the possibilities to handle the problem and our plans are to make the upload control support Integrated IIS7 mode as well.
Regarding the Medium Trust support, we will continue researching the problem, but for now we are not able to give any estimate when the RadUpload control will support Medium Trust. At the moment the only possibility to run your application in Medium trust is to put Telerik.Web.UI’s assembly in the GAC.
All the best,
the Telerik team