C#

public sealed class WindowsBackgroundService(
    MyWindowsService myWindowsService,
    ILogger<WindowsBackgroundService> logger) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        try
        {
            myWindowsService.OnStart(new string[0]);

            while (!stoppingToken.IsCancellationRequested && !myWindowsService.StopFlag)
            {
                await Task.Delay(TimeSpan.FromSeconds(1), stoppingToken);
            }
        }
        catch (OperationCanceledException)
        {
            // When the stopping token is canceled, for example, a call made from services.msc,
            // we shouldn't exit with a non-zero exit code. In other words, this is expected...
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "{Message}", ex.Message);

            // Terminates this process and returns an exit code to the operating system.
            // This is required to avoid the 'BackgroundServiceExceptionBehavior', which
            // performs one of two scenarios:
            // 1. When set to "Ignore": will do nothing at all, errors cause zombie services.
            // 2. When set to "StopHost": will cleanly stop the host, and log errors.
            //
            // In order for the Windows Service Management system to leverage configured
            // recovery options, we need to terminate the process with a non-zero exit code.
            Environment.Exit(1);
        }
    }
}

try
{
    using (RegistryKey BaseKey =
           RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64)) // Does not throw any exception
    {
        using (RegistryKey SubKey =
            BaseKey.CreateSubKey("Software\\CompanyName\\ProductName")) // The code fails here with an UnauthorizedAccessException.
        {
            DatabasePath = SubKey.GetValue("DBPath") as string;

            SubKey.Close();
            BaseKey.Close();

            return Result.Success();
        }
    }
}