IHostedService: background services must handle exceptions to avoid host shutdown

An unhandled exception in a BackgroundService.ExecuteAsync() stops the hosted service silently in .NET 5 and earlier, or shuts down the entire host in .NET 6+ (when BackgroundServiceExceptionBehavior.StopHost is the default).

Wrap the main loop in try/catch and log exceptions. Use a retry policy for transient failures:

public class WorkerService : BackgroundService
{
    private readonly ILogger<WorkerService> _logger;

    public WorkerService(ILogger<WorkerService> logger)
        => _logger = logger;

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                await DoWorkAsync(stoppingToken);
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
            {
                break; // normal shutdown, exit cleanly
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Worker iteration failed — retrying in 5s");
                await Task.Delay(TimeSpan.FromSeconds(5), stoppingToken);
            }
        }
    }
}

Configure exception behavior:

builder.Services.Configure<HostOptions>(o =>
    o.BackgroundServiceExceptionBehavior = BackgroundServiceExceptionBehavior.Ignore);

BackgroundService.ExecuteAsync is called on a fire-and-forget Task from StartAsync. In .NET 6 the host monitors this task and calls IHostApplicationLifetime.StopApplication() when it faults, bringing down the whole process.