XUpload 2.1 had a bug that inserts an extra (null) character in the Content-Type and Content-Length headers. The "cumulative" security patch released by Microsoft on 4/10/2002 (Q319733) causes IIS to reject the corrupted headers and throw the error Parameter is incorrect which in turn causes XUpload to display the error:Sending information to the server failed with error code 12030. Uploading has been aborted.
or sometimes,
Sending information to the server failed with error code 12031. Uploading has been aborted.
XUpload 2.1.0.1 fixes this bug. If you are a registered XUpload user, follow this link to obtain your free upgrade:http://support.persits.com/upgrade/upgrade.asp
To easily check what version of XUpload the browser is using, you can do this in your HTML code:
<BODY onload="Msgbox(UploadCtl.Version)" >
where UploadCtl is the name given to the control in the <OBJECT> tag.