AsyncFileUpload fails on the server

I am currently using the AsyncFileUpload in my VB.NET web app.

Locally it works perfectly, however on the server it fails to upload a small file (<9k).

I can't even seem to debug this as in JavaScript handlers I have no idea as to how to get the error reason.

function uploadError(sender,args) {

            $get("<%=LabelErr.ClientID%>").innerHTML = "Unable to Upload file for the following reason: ", "<span style='color:red;'>" + args.get_errorMessage() + "</span>";

        }

The web app can certainly write to the folder I ma trying to save the file as I handle the OnUploadedFileError event and then write a test file to make sure the server can write to the directory (this works)

Does anyone have any ideas or can point in the direction of how I can try and get the error message?

EDIT: This is a permissions issue. In the folder the client was trying to uplo开发者_JAVA百科ad to permission was denied. Can anyone indicate what user/role should be allowed access to this folder to ensure writeability

you need to grant Read/Write permission to ASPNET user, have a look on this URL and follow the steps to grant permission http://www.ironspeed.com/Designer/3.2.4/WebHelp/Part_VI/ASP_NET_User_Does_Not_Have_Permissions_to_Your_Application.htm

http://www.asp.net/learn/whitepapers/denied-access-to-iis-directories