If we add a file with forbidden extension and next try to upload , the validator signals that the action is denied. However, when we delete this file, the error message keeps appearing. Supposingly, user adds now file with correct extension but he will still get the info about wrong extension (until click on upload button that fires validation). This can be a bit confusing for users. What we would like to do is to plug additional (only client-side) validation whenever users deletes a file - we could now check if the problematic file is still selected and if not - hide the error message. The problem is - we have no onclientdeleted event defined in radupload. There is onclientdeleting (during that event we see all selected files including the one being deleted), but how we can determine whether that row (that file) is actually being deleted?