Hi,

 

When uploader throws this error, it means the server did not get any data from client side for 12 seconds.

 

Maybe the customer will also see the progress have stopped for 12 seconds before the alert be shown.

 

Network problem can cause this issue.

 

If your customer can always get such problem,

 

You can test this appSettings in web.confg:

 

<add key="CuteWebUI..AjaxUploader.UseAspNetStream" value="True" />

 

Regards,
Terry