ApplicationTrigger doesn't work with multi-instance UWP app?

Question

ApplicationTrigger doesn't work with multi-instance UWP app?

Brown, Marcus E 21

I created a UWP app and a background task. I've successfully been able to use ApplicationTrigger to trigger the background task out-of-process. I then added multi-instance support to the UWP app and since then, the ApplicationTrigger seems to do nothing. The background task does not activate; there are no exceptions or warnings of any kind; just nothing happens.

The documentation for ApplicationTrigger is here: https://learn.microsoft.com/en-us/uwp/api/windows.applicationmodel.background.applicationtrigger?view=winrt-22000

Should this trigger work in a multi-instance UWP app?

Anonymous

2022-02-18T08:00:57.283+00:00

Could you please share the detailed steps that how you added the multi-instance support in your app? Also, it would be more helpful if you could share a black app that could reproduce your issue here.
Brown, Marcus E 21 Reputation points

2022-02-18T18:13:56.15+00:00

Hi Roy! Thanks for the response!

I added the desktop4 namespace to the manifest, and to the Application element as outlined here: https://learn.microsoft.com/en-us/windows/uwp/launch-resume/multi-instance-uwp

That was it. Multi-instance seemed to work from there but the ApplicationTrigger no longer did. I I remove multi-instance, it works again. This is my first posting so I'm not sure how to create a black app for you to use to reproduce. The app I'm using is pretty close to a hello world app so imagine if you were to just create a UWP app, a background task, make it multi-instance, and attempt to trigger the background task using the ApplicationTrigger, you'll reproduce it pretty easily. In the meantime, I'll look into how to create and post an app for you to use too. Thanks!
Anonymous

2022-02-21T07:52:34.713+00:00

@Brown, Marcus E Thank you for sharing this information. I could reproduce this behavior based on your description. It is an interesting behavior. I checked the document and it only mentions that out-of-process background task is supported in multiple instance apps. I'll consult the team about this behavior. There might be some time delay.

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Anonymous

2022-02-18T08:00:57.283+00:00

Could you please share the detailed steps that how you added the multi-instance support in your app? Also, it would be more helpful if you could share a black app that could reproduce your issue here.
Brown, Marcus E 21 Reputation points

2022-02-18T18:13:56.15+00:00

Hi Roy! Thanks for the response!

I added the desktop4 namespace to the manifest, and to the Application element as outlined here: https://learn.microsoft.com/en-us/windows/uwp/launch-resume/multi-instance-uwp

That was it. Multi-instance seemed to work from there but the ApplicationTrigger no longer did. I I remove multi-instance, it works again. This is my first posting so I'm not sure how to create a black app for you to use to reproduce. The app I'm using is pretty close to a hello world app so imagine if you were to just create a UWP app, a background task, make it multi-instance, and attempt to trigger the background task using the ApplicationTrigger, you'll reproduce it pretty easily. In the meantime, I'll look into how to create and post an app for you to use too. Thanks!
Anonymous

2022-02-21T07:52:34.713+00:00

@Brown, Marcus E Thank you for sharing this information. I could reproduce this behavior based on your description. It is an interesting behavior. I checked the document and it only mentions that out-of-process background task is supported in multiple instance apps. I'll consult the team about this behavior. There might be some time delay.

Answer 1

Anonymous

Hello,

Welcome to Microsoft Q&A!

I've talked to the team about this behavior. This issue has been logged as a known issue on our list. You could also report this behavior in the Feedback Hub. But currently, there is no workaround for this behavior. Our suggestion is to avoid using the application trigger and multi-instance UWP app in the same scenario.

Thank you.

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Brown, Marcus E 21 Reputation points

2022-02-23T14:19:06.093+00:00

Ah, that's too bad. Thank you for checking Roy. Hopefully this will be addressed in the near future.
Sacha B 116 Reputation points

2023-07-15T03:44:53.2033333+00:00

I just tried to switch my app to Multi-Instanced and found the same behavior in July of 2023.
Here is a project showcasing the problem:
https://github.com/StokedOnIt/multi-instance-background-task-issue

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ApplicationTrigger doesn't work with multi-instance UWP app?

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