The following example : http://demos.telerik.com/aspnet-ajax/controls/examples/integration/gridandradasyncupload/defaultcs.aspx?product=upload
does not appear to work as expected.
If you attempt to upload an invalid file type, you correctly get the error message, but removing the invalid file does not remove the error message, and you can no longer upload a valid file.
Click on Add New Record
Select a word doc to upload.
the doc will appear with an red exclamation next to it and an error message appears below.
Remove the file, and attempt to upload a valid gif file, nothing happens. the form continues to think an invalid file is uploaded.