ajaxToolkit:AjaxFileUpload: Uploading xlsm file type gives error

Hi,

I am trying to resolve why my AjaxFileUpload is failing to upload xlsm spreadsheets. I have tested other commonly used office file formats and they seem to upload without issues.

I tried to investigate why this was happening using OnClientUploadError and for some reason the javascript function is failing to recognizeargs.get_errorMessage() as a valid function.

Any help on why I cant upload a xlsm file or why get_errorMessage() wont work will be greatly appreciated.

<ajaxToolkit:AjaxFileUpload ID="AjaxFileUpload_Modal" CssClass="ajax__fileupload_main" runat="server" padding-bottom="4" padding-left="2" padding-right="1" padding-top="4"                            ThrobberID="uploadingThrobber" OnClientUploadError="showUploadError"                            OnUploadComplete="AjaxFileUpload1_UploadComplete" OnClientUploadStart="showUploadingAnimation" OnClientUploadCompleteAll="reloadAttachments" />

function showUploadError(sender, args) {            alert(args.get_errorMessage()); (Uncaught TypeError: args.get_errorMessage is not a function)        }