UWP background task does not start after 5 times

Question

I follow https://docs.microsoft.com/en-us/windows/uwp/launch-resume/create-and-register-a-background-task to create a background task that will run every 15 minutes and ping the service .

• A Windows Runtime component project has been created with an open private class that implements IBackgroundTask

  namespace PeriodicBackgroundTask
  {
      public sealed class FifteenMinutePeriodicTimer : IBackgroundTask
      {
          private static readonly FileLogWriter mWriteLogToFile = new FileLogWriter();
          public FifteenMinutePeriodicTimer() { }
  
          public void Run(IBackgroundTaskInstance taskInstance)
          {
              try
              {
                  taskInstance.Canceled += new BackgroundTaskCanceledEventHandler(OnCanceled);
                  mDeferral = taskInstance.GetDeferral();
                  mWriteLogToFile.log("Starting periodic timer at " + DateTime.Now.ToString());
  
                  // Calling method to do a Post call to a service.
  
                  mWriteLogToFile.log("Finishing periodic timer at " + DateTime.Now.ToString());
              }
              catch (Exception ex)
              {
                  mWriteLogToFile.log("Fifteen Minute periodic timer failed.", ex);
              }
              finally
              {
                  // Adding some buffer for async processes to finish.    
                  Task.Delay(TimeSpan.FromSeconds(15)).Wait();
                  mDeferral.Complete();
              }
          }
  
          private void OnCanceled(IBackgroundTaskInstance sender, BackgroundTaskCancellationReason reason)
          {
              mWriteLogToFile.log("Fifteen minute periodic timer is canceled. {0}", reason.ToString());
          }
      }
  }
  

• Logging in to the UWP Package.appmanifest File

  <Extension Category="windows.backgroundTasks" EntryPoint="PeriodicBackgroundTask.FifteenMinutePeriodicTimer">
    <BackgroundTasks>
      <Task Type="systemEvent" />
      <Task Type="timer" />
    </BackgroundTasks>
  </Extension>
  

• Register a timer at the beginning of the OnLaunched Method in App.xaml.cs

  public async static Task RegisterBackgroundTask()
  {
      foreach (var task in BackgroundTaskRegistration.AllTasks)
      {
          if (String.Equals(task.Value.Name, TASK_NAME))
          {
              mWriteLogToFile.log("Old version of fifteen minute periodic timer found. Unregistering it.");
              BackgroundExecutionManager.RemoveAccess();
              // Unregistering so that any update in Background task can be applied.
              task.Value.Unregister(true);
              break;
          }
      }
      BackgroundAccessStatus backgroundAccessStatus = await BackgroundExecutionManager.RequestAccessAsync();
      if (backgroundAccessStatus == BackgroundAccessStatus.DeniedByUser ||
      backgroundAccessStatus == BackgroundAccessStatus.DeniedBySystemPolicy)
      {
          mWriteLogToFile.log("Fifteen minute periodic timer registration failed, due to Request access status.");
          return;
      }
  
      BackgroundTaskBuilder builder = new BackgroundTaskBuilder();
      builder.Name = TASK_NAME;
      builder.TaskEntryPoint = "PeriodicBackgroundTask.FifteenMinutePeriodicTimer";
      builder.SetTrigger(new TimeTrigger(15, false));
      builder.CancelOnConditionLoss = false;
  
      var backgroundTask = builder.Register();
      if (backgroundTask != null)
      {
          mWriteLogToFile.log("Fifteen minute periodic timer registration SUCCESSFUL.");
      }
      else
      {
          mWriteLogToFile.log("Fifteen minute periodic timer registration FAILED.");
      }
  }
  

After installing the application, FifteenMinuteBackgroundTimer starts 5 or 6 times. Sometimes 5, sometimes 6. When I try to debug a task using Visual Studio, I can debug it. I'm not sure why FifteenMinuteBackgroundTimer dies after 5 starts. Can anyone tell me how can I debug this problem?

:

Windows Build: 1607
Microsoft.NETCore.UniversalWindowsPlatform: 5.1.0

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