System.Threading.ThreadAbortException: Thread was being aborted. error on workflowfileupload element

Hi, we are getting an error when users click on an attached file using the workflowfileupload element.

Our code in the Default.aspx that shows the file upload is:

<%@ Register Assembly="WorkflowGen.My.Web.UI.WebControls" Namespace="WorkflowGen.My.Web.UI.WebControls" TagPrefix="cc1" %>

<cc1:workflowfileupload id="COMMITTEE_CHAIR_LETTER_OF_RESERVATIONS" runat="server" AddText="Attach" UpdateText="Modify"></cc1:workflowfileupload>

Here’s a screenshot of the error described:

Can you please provide guidance as to how to deal with this?