In IE10 (on both Windows 7 and Windows 8), if you select a file to be uploaded, then remove it, you are then unable to select a new file. The file selection dialog opens when the "Select File" button is clicked, and you can select a file, but the file information is not displayed, and clicking the "Upload" button does nothing. Something is obviously not quite getting cleared out when removing the previously selected file.
This can all be seen using the sample site: http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/AjaxFileUpload/AjaxFileUpload.aspx
Comments: I just verified by doing the following IE 10 Go to page Click Select File Browse to JPG file Once added (Pending) Click Remove Click Select File Browse to JPG file File is not added Then I did the following and go the same behavior Go to page Click Select File Browse to JPG file Once added (Pending) Click Upload File uploads and displays Click Select File Browse to JPG file File is not added Switched my browser to IE9 (F12) Developer Tools - Browser Mode IE9 Performed the above steps and everything worked correctly. So does look to be specific to IE10
This can all be seen using the sample site: http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/AjaxFileUpload/AjaxFileUpload.aspx
Comments: I just verified by doing the following IE 10 Go to page Click Select File Browse to JPG file Once added (Pending) Click Remove Click Select File Browse to JPG file File is not added Then I did the following and go the same behavior Go to page Click Select File Browse to JPG file Once added (Pending) Click Upload File uploads and displays Click Select File Browse to JPG file File is not added Switched my browser to IE9 (F12) Developer Tools - Browser Mode IE9 Performed the above steps and everything worked correctly. So does look to be specific to IE10