Cast exception when trying to create new Task Schedueler task.

Question

I'm attempting to create a new task in the Windows Task Scheduler in C#. What I've got so far is pretty much a copy and paste of http://bartdesmet.net/blogs/bart/archive/2008/02/23/calling-the-task-scheduler-in-windows-vista-and-windows-server-2008-from-managed-code.aspx

Everything compiles just fine but come run time I get the following exception:

Unable to cast COM object of type 'System.__ComObject' to interface type 'TaskScheduler.ITimeTrigger'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{B45747E0-EBA7-4276-9F29-85C5BB300006}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).

Here's all the code so you can see what I'm doing here without following the above link.

TaskSchedulerClass Scheduler = new TaskSchedulerClass();

Scheduler.Connect(null, null, null, null);

ITaskDefinition Task = Scheduler.NewTask(0);

Task.RegistrationInfo.Author = "Test Task";

Task.RegistrationInfo.Description = "Just testing this out.";

ITimeTrigger Trigger = (ITimeTrigger)Task.Triggers.Create(_TASK_TRIGGER_TYPE2.TASK_TRIGGER_DAILY);

Trigger.Id = "TestTrigger";

Trigger.StartBoundary = "2010-05-12T06:15:00";

IShowMessageAction Action = (IShowMessageAction)Task.Actions.Create(_TASK_ACTION_TYPE.TASK_ACTION_SHOW_MESSAGE);

Action.Id = "TestAction";

Action.Title = "Test Task";

Action.MessageBody = "This is a test.";

ITaskFolder Root = Scheduler.GetFolder("\\");

IRegisteredTask RegisteredTask = Root.RegisterTaskDefinition("Background Backup", Task, (int)_TASK_CREATION.TASK_CREATE_OR_UPDATE, null, null, _TASK_LOGON_TYPE.TASK_LOGON_INTERACTIVE_TOKEN, "");

The line that is throwing the exception is this one

ITimeTrigger Trigger = (ITimeTrigger)Task.Triggers.Create(_TASK_TRIGGER_TYPE2.TASK_TRIGGER_DAILY);

The exception message kinda makes sense to me, but I'm afraid I don't know enough about COM to really know where to begin with this.

Also, I should add that I'm using VS 2010 and I had to set the project to either be for x86 or x64 CPU's instead of the usual "Any CPU" because it kept giving me a BadImageFormatException. I doubt that's related to my current problem, but just in case I thought I might as well mention it.

Answer 1

You are using a different enumeration value, for TASK_TRIGGER_DAILY you will get an IDailyTrigger, not an ITimeTrigger.

See this MSDN page.