ObservableCollection does not work for Microsoft Store version while working for debug version

Question

ObservableCollection does not work for Microsoft Store version while working for debug version

Hong 1,566

The following code is solely for debugging.

Xaml:

        <ListView x:Name="listViewTest"/>

C#:

                var folders = new ObservableCollection<string>
                    {
                        "OBS 1",
                        "OBS 2",
                        "OBS 3"
                    };

                listViewTest.ItemsSource = folders;

This works exactly as expected if the WinUI app is started from VS2026, but the store version built by VS2026 shows nothing.

The following works for both the debug version and the store version:

                var folders = new c<string>
                    {
                        "OBS 1",
                        "OBS 2",
                        "OBS 3"
                    };

                listViewTest.ItemsSource = folders.ToList();

My app has a slightly complex list, and it works flawlessly with the debug version, but not with the store version. It took me many hours to narrow it down to ObservableCollection.

Could anyone shed some light on this?

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Answer 1

Jay Pham (WICLOUD CORPORATION) 4,435 Microsoft External Staff Moderator

I am working the issue and will provide an update soon. Thank you for your patience.

Hong 1,566 Reputation points

2026-09-11T02:08:58.9+00:00

Thanks a lot for the help.

I am trying to migrate my UWP apps to WinUI for the 3rd time. I tried twice and found WinUI unstable and unpredictable. I have just started to use VS 2026 and am hoping WinUI has improved. I read that AOT is more predictable than .Net Native.
Jay Pham (WICLOUD CORPORATION) 4,435 Reputation points Microsoft External Staff Moderator

2026-09-11T02:29:00.7533333+00:00
Hi @Hong ,

Thank you for sharing that context. I understand how frustrating it must be to encounter another issue on your third attempt to migrate from UWP to WinUI.

To help narrow down this specific issue, could you confirm whether Native AOT is enabled in your current WinUI project, or whether you are considering using it? If you’re unsure, please share your .csproj and publish profile with sensitive information removed.

Could you also check whether the ListView is empty when:

Running Release in Visual Studio.

Installing a Release MSIX package locally, without going through Microsoft Store.

Those results will help us distinguish a build/publish configuration issue from something specific to the Store-installed package.
Hong 1,566 Reputation points

2026-09-11T03:16:25+00:00
I was so confused that I thought AOT was used automatically.

This is from the project file:

<PropertyGroup>  <PublishReadyToRun Condition="'$(Configuration)' == 'Debug'">False</PublishReadyToRun> <PublishReadyToRun Condition="'$(Configuration)' != 'Debug'">True</PublishReadyToRun>  <PublishTrimmed Condition="'$(Configuration)' == 'Debug'">False</PublishTrimmed> <PublishTrimmed Condition="'$(Configuration)' != 'Debug'">True</PublishTrimmed> <SupportedOSPlatformVersion>10.0.19041.0</SupportedOSPlatformVersion> </PropertyGroup>

My original question shows ALL the code involving listViewTest, so I am not sure what you mean by "whether the ListView is empty".

After hours of debugging this issue, I realized that the version published to the Microsoft Store behaves exactly the same as the version installed using the submitted app package (i.e., the .msixbundle file), so I have been testing the store version by installing the package locally to save time.

BTW, I should have mentioned that both the release and debug versions started by VS 2026 work flawlessly. Only the store version has this issue.
Jay Pham (WICLOUD CORPORATION) 4,435 Reputation points Microsoft External Staff Moderator

2026-09-11T06:23:01.09+00:00
Hi @Hong ,

Thank you for clarifying, and sorry my earlier question was unclear. I understand now that both Debug and Release work when launched from Visual Studio, while the published package fails whether installed locally or from the Store.

PublishReadyToRun enables ReadyToRun compilation, which is different from Native AOT. The setting I would investigate first is PublishTrimmed, since trimming happens during publishing and can introduce runtime issues. This is a hypothesis to test, not a confirmed cause. learn.microsoft.com

Could you temporarily change your existing non-Debug trimming setting to:

<PublishTrimmed Condition="'$(Configuration)' != 'Debug'">False</PublishTrimmed>

Please leave PublishReadyToRun unchanged, ensure the publish profile does not override this setting, then clean/rebuild and generate a fresh package. Installing it locally is sufficient for this test—there is no need to submit it to the Store.

Does the ObservableCollection example display correctly with that package?

Also, your comment mentions that trimming must remain enabled to avoid crashes. Have you actually encountered a crash with trimming disabled, or was that comment included in the template? If you encountered one, please share the error details.

Thank you.
Hong 1,566 Reputation points

2026-09-11T09:56:32.6533333+00:00

The comment about the crash was a result of spending days debugging the mystery store version crash last year. I confirmed the crash by reproducing it five times in a row with PublishTrimmed disabled yesterday.