When I add docx or pptx to the list of allowed file extentions, the filtering no longer works in the HTML5 file browser. It does still work in Flash.  

I am using dotNet 4.0 Webforms.

Hi mharcement,

The dialog filter function is based on silverlight and flash plug-in, if you are using the html5 upload mode, then the control will check the file extension at server side, so it will not makes the client upload the wrong extension file.

Regards,

Ken 

http://ajaxuploader.com/demo/simple-upload-Validation.aspx

That demo works without flash or silverlight and shows only custom files.  If I don't add docx or pptx to the extention list then I can reproduce your demo. How do I make it work with docx and pptx?

Hi mharcement,

the html5 mode can not limit the user to select what file extensions, it only work for silverlight and flash mode. Like the screenshot below.

maybe you can set the silverlight and flash upload mode in a higher priority. like the code below.

 <CuteWebUI:Uploader runat="server" ID="Uploader1" UploadTypePriority="Silverlight,Flash,HTML5">
        </CuteWebUI:Uploader>
 

Regards,

Ken