COMException when calling NotificationComServer.CreateAndRegisterActivator

[Bondarenko1990]

I get a crash on startup related to Windows notifications.

System.Runtime.InteropServices.COMException
Unexpected HRESULT has been returned from a call to a COM component.
at Notifications.Windows.NotificationComServer.CreateAndRegisterActivator(Guid)

Environment:

• OS: Windows 10.0.18363 (Version 1909)
• Avalonia: 11.3.6
• Notifications.Windows from Avalonia.Labs

Steps to Reproduce:

1. Run the app on Windows 10 1909
2. Trigger notification registration
3. Observe crash

[emmauss]

Ensure you've either set your AppUserModelId in AppNotificationOptions, or if you are using a win32 packaged project, the ComActivatorGuidOverride.

.WithAppNotifications(new AppNotificationOptions()
{
    ...
    AppUserModelId = "com.Avalonia.Labs.Catalog",
    // Is required for Packaged project, optional for the rest.
    // ComActivatorGuidOverride = Guid.Parse("67890354-2A47-444C-B15F-DBF513C82F03")
})

[Bondarenko1990]

@emmauss Thanks for the suggestion. I’ve already set the AppUserModelId in AppNotificationOptions, and my app is not a Win32 packaged project.
Here’s the relevant part of my setup:

.WithAppNotifications(new AppNotificationOptions()
{
    AppIcon = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), Title) + "\\Images\\Icon.ico",
    AppName = Title,
    AppUserModelId = Name
})

[Bondarenko1990]

Thanks again for the help. Just to clarify:
• I'm running on Windows 10 version 1909 (build 18363), which might be relevant since it's quite old.
• The app is not packaged (no MSIX or installer manifest), just a standalone .exe.
• I’ve set AppUserModelId, and I’m not using ComActivatorGuidOverride.

Here’s what I’m still unsure about:
• Does NotificationComServer.CreateAndRegisterActivator(Guid) require any registry setup or OS-level support that might be missing on older Windows builds?
• Could this crash be related to missing Windows Notification Platform components or permissions?
• Is there a way to gracefully detect and skip notification registration if the platform doesn’t support it?

I would be happy to try something else to solve the problem and help narrow down the search.

[emmauss]

Could you provide the full stacktrace of the exception?

[Bondarenko1990]

System.Runtime.InteropServices.COMException
Unexpected HRESULT has been returned from a call to a COM component. HResult 0x80004015

MyApp.Notifications.Windows.NotificationComServer in CreateAndRegisterActivator(Guid)
MyApp.Notifications.Windows.NativeNotificationManager in Initialize(AppNotificationOptions)
MyApp.Notifications.AppBuilderExtensions.<>c__DisplayClass0_0 in <WithAppNotifications>b__0(AppBuilder a)
Avalonia.AppBuilder in SetupUnsafe()
Avalonia.ClassicDesktopStyleApplicationLifetimeExtensions in StartWithClassicDesktopLifetime(AppBuilder builder, String[] args, Action`1 lifetimeBuilder)
MyApp.Program in Main(String[] args)

[emmauss]

Are you running a modified or non-default version of windows 10? The error is only reported when the app can't connect to the COM server as the logged in user. Does the current user have admin permissions or is a local user?

[Bondarenko1990]

Thanks for the follow-up. Yes, this is a modified version of Windows 10 (1909), and the app only runs under an administrator account. App runs via UAC.
Given that, could the COM server registration be failing due to missing components or altered security policies in this Windows build? Is there a way to verify that the required COM infrastructure for notifications is intact?
Also, is there a fallback or safe way to detect whether notification registration is supported before calling CreateAndRegisterActivator?

[emmauss]

Are users or apps able to create registry keys on your system? We can offer little help if the issue is from a misconfigured system, especially for a OS feature such as COM where a single change can make apps not work.

If registry keys can be created, confirm that SOFTWARE\\Classes\\CLSID\\X\\LocalServer32 is created with the full path of the exe as value. X is the guid of the app, so you would have to check each key in CLSID to find the one the app creates at runtime

Your best alternative is to use a packaged project for your app. That should handle all com registrations for you,

[Bondarenko1990]

I've encountered a COM server activation error in Event Viewer (Source: DistributedCOM) related to the following CLSID and APPID:
• CLSID: {C2F03A33-21F5-47FA-B4BB-156362A2F239}
• APPID: {316CDED5-E4AE-4B15-9113-7055D84DCC97}
The error message states:
"The machine-default permission settings do not grant Local Activation permission for the COM Server application [...] to the user NT AUTHORITY\LOCAL SERVICE SID (S-1-5-19) [...] This security permission can be modified using the Component Services administrative tool."

According to the registry, this CLSID corresponds to Immersive Shell. The affected environment seems to involve a distributed system with domain configuration.

I’m trying to understand the purpose of the call to CreateAndRegisterActivator.RegisterComServer(Guid guid) in the Avalonia Labs codebase. In my case, I disabled COM server registration by setting DisableComServer = true in AppNotificationOptions, like so:
.WithAppNotifications(new AppNotificationOptions

{
    AppIcon = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), Title) + "\\Images\\Icon.ico", 
    AppName = Title,
    AppUserModelId = Name,
    DisableComServer = true,
})

After this change, the error no longer appears and everything works as expected.
My application is installed via a WiX installer and runs with administrative privileges. Notifications are created and shown by the application itself while it's running, I don't rely on external triggers or background COM activation. Could someone clarify why COM server registration is needed here, and whether disabling it is a safe long-term solution?

Also, do you have any recommendations for best practices in this scenario? For example:
• Should I explicitly configure DCOM permissions via Component Services?
• Is disabling the COM server the preferred approach for production deployments?
• Or maybe the code could check whether registry write access is available before calling CreateAndRegisterActivator.RegisterComServer(Guid guid), and skip RegisterComServer if not?
Any insights or suggestions would be greatly appreciated.

[emmauss]

Disabling the COM server would prevent app activation if there is no process running. If you do not need that, you can disable it. That is why we have the option there. It's useful when you don't want any trace of your app in registry.

[Bondarenko1990]

Now I get an error when the app shows a notification and crashes.
System.Runtime.InteropServices.COMException in NativeNotificationManager.Show(NativeNotification nativeNotification)
WinRT.Impl.__MicroComIToastNotifierProxy in Show(IToastNotification).
How can I fix this error?

[emmauss]

Provide full stack trace. Do you have com server enabled

[Bondarenko1990]

Provide full stack trace. Do you have com server enabled

How to check if a COM server is enabled or disabled?

[emmauss]

K though you were planning on setting this, DisableComServer = true

[Bondarenko1990]

K though you were planning on setting this, DisableComServer = true

Yes, "DisableComServer = true".