Setting SystemTrigger or ApplicationTrigger as background task triggers throws exception when registering

[Diegorro98]

Describe the bug

I'm looking to create Win32 COM background task with Time, System and Application Triggers. Time works, but when System or Application triggers are set, calling BackgroundTaskBuilder.Register throws the following exception

System.Runtime.InteropServices.COMException: "Incompatible request (0x80070032)"

Steps to reproduce the bug

In BackgroundTaskWinMainComSample/CS project from DesktopBridgeToUWP-Sample repository I'm able to replicate the issue.

Only thing needed to update is at MainWindow.xaml.cs:172, change the Time trigger by any of the others mentioned:

RegisterBackgroundTaskWithSystem(new SystemTrigger(SystemTriggerType.SessionConnected, false), typeof(TimeTriggeredTask).GUID, typeof(TimeTriggeredTask).Name);

RegisterBackgroundTaskWithSystem(new ApplicationTrigger(), typeof(TimeTriggeredTask).GUID, typeof(TimeTriggeredTask).Name);

Expected behavior

It should be able to register the task and triggers should work.

Screenshots

No response

NuGet package version

Windows App SDK 1.4.0: 1.4.230822000

Packaging type

Packaged (MSIX)

Windows version

Insider Build (xxxxx)

IDE

Visual Studio 2022

Additional context

No response

[stevenbrix]

@bpulliam what's the status here?

[tipa]

Same issue here, I am trying to use new SystemTrigger(SystemTriggerType.TimeZoneChange, false)

[godlytalias]

Currently we support SystemTrigger with the newly added BackgroundTaskBuilder API in WinAppSDK 1.7 exp1 release, Sample : microsoft/WindowsAppSDK-Samples#392

[Diegorro98]

Thank you a lot for the info and for the sample, it works perfectly!
However, I'm trying to use these triggers on my app that uses C#, but I still get the same exception type (but this time the exception message is empty) with those triggers.
Would you mind to include a C# sample? that would help a lot

[Osirisoo0O]

Currently we support SystemTrigger or ApplicationTrigger with the newly added BackgroundTaskBuilder API in WinAppSDK 1.7 exp1 release, Sample : microsoft/WindowsAppSDK-Samples#392

Can you provide a C# sample？Thanks！

[godlytalias]

@Diegorro98 @Osirisoo0O
I have added C# sample here: microsoft/WindowsAppSDK-Samples@e123eae
Please let me know whether it helps, Thanks

[Diegorro98]

Hey! I was finally able to make it work at my app :) Thank you!

It has been a little bit difficult because I was adapting the code that you uploaded to the code from my app, I was having exceptions all the time, but I finally discovered because I was using Windows.ApplicationModel.Background.BackgroundTaskBuilder (BackgroundTaskBuilder was imported with using) and I didn't saw that you were using Microsoft.Windows.ApplicationModel.Background.BackgroundTaskBuilder.
I hope this can be useful for someone encountering the same problem I was having.

Btw, is LaunchAndActivationPermission="O:PSG:BUD:(A;;11;;;IU)(A;;11;;;S-1-15-2-1)S:(ML;;NX;;;LW)" at Package.appxmanifest's com:ExeServer something important? I saw that you used but it also works without it and I would like to know what is and why are you adding it to your example

[godlytalias]

Thanks a lot @Diegorro98 for trying it out and the feedback. Microsoft.* is the newly added WinAppSDK API. I will update sample to highlight that usage as well with a comment.
LaunchAndActivationPermission is ideally required for giving the permission for OOP Background Task to launch the COM component in your package, without which it may throw access denied issues during COM activation.

[Diegorro98]

I just have been testing more, and yesterday in fact I was only able to register the task. Although the task is registered it does not launch the Run method from the class that inherits from IBackgroundTask. It launches the backgroundTaskHost.exe but does not do anything else, and after some time, it dies.

I have created a patch for the example at microsoft/DesktopBridgeToUWP-Samples/tree/master/Samples/BackgroundTaskWinMainComSample/CS were I tried to set everything similar to the provided example and the mentioned issue happens: new_bg_task.patch

EDIT: I created a fork with the changes to make things easier: Diegorro98/DesktopBridgeToUWP-Samples/Samples/BackgroundTaskWinMainComSample/CS

[Diegorro98]

I also discovered that the CS version, when the background task is triggered the app gets opened, and once you click the register button (which it was already clicked before, because if not the task wouldn't have been triggered) it does run the background task. The only thing that I have changed from your version is the Microsoft.Windows.SDK.BuildTools version because 10.0.26100.2454 is not available and I used the latest available (10.0.26100.1742).

[godlytalias]

In the patch it seems you are removing the call to RegisterProcessForBackgroundTask which is actually doing the CoRegisterClassObject which registers the activation factory for COM activation. Without this COM activation will fail and that is why you're seeing the backgroundtaskhost.exe coming up and then dies without being able to activate your COM component

[Diegorro98]

I see, my bad I deleted it for no reason.
I did the change but it happens the same issue: https://github.com/Diegorro98/DesktopBridgeToUWP-Samples/commit/4ef17a52210090f63be54c473a396cc0f27409e2