System.ArgumentException: Illegal characters in path.
   at System.IO.Path.CheckInvalidPathChars(String path)
   at System.IO.Path.GetExtension(String path)
   at System.ServiceModel.Activation.HttpModule.ProcessRequest(Object sender, EventArgs e)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)