"Task was canceled" error on Azure website

Question

As traffic to our Azure site increases, we see an increasing number of "Task was canceled" errors. A typical trace might look like this:

Fatal web api error: Controller: CustomerUserEventsController; 
Url: http://app.payboard.com/api/organizations/9ddf55d1-e0c1-4a8f-9327-eef38682e090/addcustomeruserevent?callback=jQuery210035782216349616647_1398442710964&cookieId=05be2755-dc0d-414d-b0d2-ea1986a929c3&customerId=&customerName=&customerUserId=&customerUserFirstName=&customerUserLastName=&eventName=hr-index-GET&_=1398442710965; 
Error: A task was canceled. ( at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Controllers.ExceptionFilterResult.<ExecuteAsync>d__0.MoveNext())

Previously, we could receive one day; it gradually increased, so now we get a couple of dozen.

You will notice that in the stack trace there is only a frame code - none of our codes exist. Therefore, I am a bit in trouble to troubleshoot. Any suggestions on how to approach tracking them?

Answer 1

See the answer here:

ASP.NET Web API OperationCanceledException,

WebAPI :

http://aspnetwebstack.codeplex.com/workitem/1797

, , HTTP- , , , . , , :

/// <summary>
/// See /questions/65674/aspnet-web-api-operationcanceledexception-when-browser-cancels-the-request
/// </summary>
public class CancelledTaskBugWorkaroundMessageHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var response = await base.SendAsync(request, cancellationToken);

        // Try to suppress response content when the cancellation token has fired; ASP.NET will log to the Application event log if there content in this case.
        if (cancellationToken.IsCancellationRequested)
        {
            return new HttpResponseMessage(HttpStatusCode.InternalServerError);
        }

        return response;
    }
}