System.Threading.Tasks.TaskCanceledException: A task was canceled.
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Insurance.Controller.ProposalController.<UploadfileondropboxnewAsync>d__6.MoveNext() in C:\CODES\MailProject\Insurance\Controller\ProposalController.cs:line 203