Windows.BackgroundTasks contract or is not installed

Yesterday I did some work on BackgroundTasks (CS) for customer application, while building the structure I faced an unfamiliar error and application crash when the Task was triggered.

I’ve look into Windows Event Log and fond a error related to my application:

Activation of app fcf446e9-4a89-4d56-b3ae-def1bab41ac2_d824bndbbbqn4!App failed with error: This app does not support the contract specified or is not installed. See the Microsoft-Windows-TWinUI/Operational log for additional information.

So where can you find the “Microsoft-Windows-TWinUI/Operational“ log?

Expend “Application and Services Logs” folder, Microsoft –> Windows –> Apps

Now I can see more details message of error:

The app fcf446e9-4a89-4d56-b3ae-def1bab41ac2_d824bndbbbqn4!App is not registered for the Windows.BackgroundTasks contract or is not installed.

First I’ve verified that "ALL APPLICATION PACKAGES" role is present for "Packages" directory in the Local\AppData directory of the current user.

Second I make sure application package manifest declared Background Tasks and set the Task entry point.

Last I check if there is project reference between the Tasks project and my application project.

And I forgot to add reference…

Tasks as isolated from you application but when those Tasks invoked they need reference to the registered application.

Hope this helps.