Enable debugging in SharePoint

Open C:\Inetpub\wwwroot\wss\VirtualDirectories\sitedir\web.config You should also configure your SharePoint site to display any error messages that are generated by setting the customErrors tag's mode attribute to Off (the default setting suppresses all error messages): To get the full list of called modules listed on the error screen, you'll also need to set the SafeMode's CallStack attribute to "true":