[Win-UI] : Not able to add the background tasks Windows.ApplicationModel.Background.IBackgroundTask

[MoueenShaik]

Describe the bug
I am trying to add BackgroundTasks which is a type of Windows.ApplicationModel.Background.IBackgroundTask as per the below Microsoft doc in WINUI
https://docs.microsoft.com/en-us/windows/uwp/launch-resume/create-and-register-a-background-task

To achieve my requirement, added the background tasks under the declaration tab in the Package.appmanifest.

After adding the background tasks and tried to build the solution but unfortunately, I am getting the below exception.

To fix the above issue one of the technical forum suggested that adding an audio task will get resolved.
Adding an audio task to the package.manifest file, build issue got resolved, But when I launch the application getting the below exception

FYI :
Visual Studio version: Visual Studio Enterprise 2019 Preview - 16.7.30128.36
.Net SDK : Microsoft .NET SDK 5.0.100-preview.5.20279.10(x86)
WinUIVersion : 3.0.0-preview2.200713.0
csproject:

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Create a new Blank app packaged,(WINUI in Desktop)
2. Add a new class with inherit from IBackgroundTask
3. Add background-tasks to the package.Manifest under declaration tab.
4. Build the solution.

Expected behavior
Application should build/run

Version Info

NuGet package version:
[Microsoft.WinUI 3.0.0-preview2.200713.0]

Windows app type:

UWP	Win32

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
October 2020 Update (19042)
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop
Xbox
Surface Hub
IoT

Could you please guide/help me on how to add background tasks in winUI desktop application without exceptions? and let me know if you need any other details from my end.

Thanks & regards,
Moueen Shaik

[StephenLPeters]

Can you please first try upating your Winui3 version from Preview 2 to Preview 4?

[ghost]

This issue has been automatically marked as stale because it has been marked as requiring author feedback but has not had any activity for 7 days. It will be closed if no further activity occurs within 7 days of this comment.

[shahidjaved]

You can try adding another extentisions tag in Package manifest file. like below image it is working for me.