c# - 未处理的异常。System.ArgumentNullException：值不能为空。（参数“名称或连接字符串”）

Question

我在我的 ASP.net 核心应用程序中使用 hangfire 来运行一些后台任务。我正在使用 IIS，我已将 Hangfire 配置如下：

using Hangfire;

namespace Whm.APIPortal
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddHangfire(option =>
            {
                option.UseSqlServerStorage(Configuration.GetConnectionString("HangFireConnection"));
            });
            services.AddHangfireServer();
         }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });

            app.UseHangfireDashboard();

            app.UseHangfireServer();
         }
     }
}

下面是我的 appsettings.json 文件

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "ConnectionStrings": {
    "DefaultConnection": "Server=.\\SQLEXPRESS;Database=Whm;User Id=sa;Password=***;MultipleActiveResultSets=true",
    "HangFireConnection": "Server=.\\SQLEXPRESS;Database=WhmHangFire;User Id=sa;Password=***;"
  },
  "AllowedHosts": "*"
}

每当我尝试启动应用程序时，我都会遇到异常

Unhandled exception. System.ArgumentNullException: Value cannot be null. (Parameter 'nameOrConnectionString')

我在我的 sql 服务器上创建了数据库“WhmHangFire”。

我仍然得到同样的例外。有人可以解释是什么导致了这个问题吗？

谢谢