RadUpload has been replaced by RadAsyncUpload, Telerik’s next-generation ASP.NET upload component.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.
When you try to use the RadUpload, the UploadedFiles collection has no files inside.
There are two possible reasons for the problem:
You have set File Validation and the the uploaded files are considered invalid.
You are using a Button or other control which causes postback is using AJAX to make an asynchronous postback. This can be because
It is placed inside RadAjaxPanel (or UpdatePanel)
It has an associated AjaxSetting (RadAjax)
It has an associated Trigger (ASP.NET AJAX)
If the reason for the problem was the File Validation, try adjusting the File Validation properties, such as AllowedFileExtensions, AllowedMimeTypes and MaxFileSize.
If the reason for the problem was an asynchronous postback, try removing the control that makes the postback (callback) from the AjaxPanel or UpdatePanel, or remove its associated AjaxSetting or Trigger. The Uploading Files with AJAX topic describes additional approaches you can take.
RadAjax, ASP.NET AJAX or any other similar framework for asynchronous calls uses the XmlHttpRequest component to make its callback requests to the web application. This component is not able to upload files.