Which build/version of the RadUpload are you using? We made some changes around the UI related code of the control so we recommend using the Q3 release build or later. If you are using those builds, is it possible to provide us with some steps to reproduce the problem so that we can resolve it. I have tested this with our internal builds and it works correctly. However, I noticed an issue when IsAutomaticUpload is set to True and the upload is canceled in the UploadStarted event. We will resolve this for the next internal build. What I would recommend is to use the FileUploadStarting event and cancel it instead (e.Handled = true).
the Telerik team
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