Program.cs

using System;
using System.Threading.Tasks;
using Avalonia;
using Avalonia.Controls.ApplicationLifetimes;
using Avalonia.Markup.Xaml;

namespace FIXSniff;

public partial class App : Application {
    public override void Initialize() {
        AvaloniaXamlLoader.Load(this);
    }

    public override void OnFrameworkInitializationCompleted() {
        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop) {
            desktop.MainWindow = new MainWindow();
            
            // Handle shutdown gracefully to avoid D-Bus exceptions
            desktop.ShutdownRequested += OnShutdownRequested;
        }

        base.OnFrameworkInitializationCompleted();
    }

    private void OnShutdownRequested(object? sender, ShutdownRequestedEventArgs e) {
        // Give time for cleanup
        try {
            Task.Delay(100).Wait();
        } catch {
            // Ignore any cleanup exceptions
        }
    }
}

public class Program {
    public static void Main(string[] args) {
        try {
            BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
        } catch (TaskCanceledException) {
            // Ignore D-Bus cleanup exceptions on Linux
        } catch (Exception ex) when (ex.Message.Contains("DBus")) {
            // Ignore D-Bus related exceptions during shutdown
        }
    }

    public static AppBuilder BuildAvaloniaApp() => AppBuilder
        .Configure<App>()
        .UsePlatformDetect()
        .WithInterFont()
        .LogToTrace()
    ;
}