I find it a disconcerting that when the uploads have completed one is only offered the options to "Cancel" or "Add more files".  Clicking on "Cancel" seems like you are going to stop whatever you were doing which is not the case because "Cancel" only resets the session after the uploads have completed and you really can't cancel anything.  I would like to propose that the "Cancel" button switches to "Done" to give a clearer indication of what the options are.

If one adds more files or a session is in progress then it is appropriate for the "Cancel" to be visible.

Change the StartUpload() method implementation so that it can work while the RadUpload control is disabled.

Add properties for customizing the upload appearance to allow the upload too look like an ordinary single file upload box.

The current error reporting UI is not very UX. We need to improve it.

Available in R2 2016 Release

Incorrect UI state when validating all files with the Validate event. 

The Upload does not pass data set in the args of its FileUploadStarting event. The values set in the args are send only for the first chunk, all chunks after that does not have that data.

 The last response of contains incorrect information (it contains data from the previously uploaded chunk).

Available in LIB version: 2016.3.1010

This happens if the file is not first in the selected files list.

Steps to reproduce:

1. Add 2 files for upload. The first one should be bigger so you have time do to the next steps.
2. Click the Upload button. The first starts to upload.
3. Delete the second file.

When the upload process gets to the second file, a NullReferenceException is thrown.