ASP Uploader need to transfer the upload files to the server, so the postback is necessary.
 
If you just want to prevent it, you can try the code below
 
<script>
function CuteWebUI_AjaxUploader_OnPostback()
{
 return false;
}
</script>
 
 If you want to submit the page after all your logic, please use the start uploading manually example. Below is the demo link
 
http://aspuploader.com/demo/form-manualstart.asp 

 

Thank you for asking

Eric@cutesoft.net