.NET Core 2.0中Hangfire服务依赖Scoped DbContext的DI报错问题

刚把项目从.NET Core 1.1升级到2.0，就遇到了个头疼的问题——之前好好的代码现在报错了：

Cannot consume scoped service 'ArithmosDaily.Data.ArithmosContext' from singleton 'ArithmosDaily.IHangfireJobSchedulerService'.

我的场景是用Hangfire做定时任务，需要通过依赖注入DbContext来从API拉数据更新数据库。DbContext是默认的Scoped实例，而Hangfire的调度服务我之前注册成了Singleton——在1.1版本里框架没检查这种Scoped被Singleton消费的情况，所以一直运行正常。

后来我试着把IHangfireJobSchedulerService改成Scoped注册，结果又出现新错误：

Cannot resolve scoped service 'ArithmosDaily.IHangfireJobSchedulerService' from root provider.

我还尝试过用services.BuildServiceProvider(false);关闭范围验证，但完全没效果。下面是我Startup类里的ConfigureServices和Configure方法代码，有没有大佬能指点一下？

public void ConfigureServices(IServiceCollection services) 
{ 
    services.BuildServiceProvider(false); 
    string conn = Configuration.GetConnectionString("Arithmos"); 
    services.AddDbContext<ArithmosContext>(options => options.UseSqlite(conn)); 
    services.AddMvc(); 
    services.AddHangfire(x => x.UseSQLiteStorage(conn)); 
    services.AddScoped<IHangfireJobSchedulerService, HangfireJobSchedulerService>(); 
} 

public void Configure(IApplicationBuilder app, IHostingEnvironment env, IApplicationLifetime lifetime) 
{ 
    lifetime.ApplicationStarted.Register(OnStartup); 
    lifetime.ApplicationStopping.Register(OnShutdown); 

    if (env.IsDevelopment()) 
    { 
        app.UseDeveloperExceptionPage(); 
        app.UseBrowserLink(); 
    } 
    else 
        app.UseExceptionHandler("/Error"); 

    app.UseStaticFiles(); 

    app.UseMvc(routes => 
    { 
        routes.MapRoute( 
            name: "default", 
            template: "{controller}/{action=Index}/{id?}"); 
    }); 

    app.UseHangfireServer(); 
    app.UseHangfireDashboard(options: new DashboardOptions { Authorization = new[] { new HangfireAuthorizationFilter() } }); 

    jobSchedulerService = app.ApplicationServices.GetRequiredService<IHangfireJobSchedulerService>(); 
}

内容的提问来源于stack exchange，提问作者Robert Burke