ASP.NET Core 6.0：值不能为空。参数名称：starter中的connectionString appsettings.json

问：

我正在尝试从我的文件中获取我的连接字符串并在我的启动文件中使用它，但我不断收到错误appsettings.json

值不能为 null。参数名称：connectionString。

这是我的文件：Appsetting.json

{
  "Project": {
    "ConnectionStrings": "Data Source=(local)\\SQLSERVER; Database=RecommendationSite; Persist Security Info=false; User ID='sa'; Password='sa'; MultipleActiveResultSets=True; Trusted_Connection=False;",
    "CompanyName": "RecommendationSite1 ",
    "CompanyPhone": "+7 (111) 111-11-11",
    "CompanyPhoneShort": "+71111111111",
    "CompanyEmail": "[email protected]"
  }
}

尝试读取该连接字符串的方法：Startup.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using RecommendationSite.Data;
using RecommendationSite.Domain.Repositories.Abstract;
using RecommendationSite.Domain.Repositories.EntityFramework;
using RecommendationSite.Domain;
using RecommendationSite.Service;
using Microsoft.AspNetCore.Identity;

namespace RecommendationSite
{
    public class Startup
    {
        public IConfiguration Configuration { get; }
        public Startup(IConfiguration configuration) => Configuration = configuration;

        // This method gets called by the runtime. Use this method to add services to the container.

        public void ConfigureServices(IServiceCollection services)
        {
            Configuration.Bind("Project", new Config());

            services.AddTransient<ITextFieldsRepository, EFTextFieldsRepository>();
            services.AddTransient<IServiceItemsRepository, EFServiceItemsRepository>();
            services.AddTransient<DataManager>();

            services.AddDbContext<AppDbContext>(x => x.UseSqlServer(Config.ConnectionString));

            services.AddIdentity<IdentityUser, IdentityRole>(opts =>
            {
                opts.User.RequireUniqueEmail = true;
                opts.Password.RequiredLength = 6;
                opts.Password.RequireNonAlphanumeric = false;
                opts.Password.RequireLowercase = false;
                opts.Password.RequireUppercase = false;
                opts.Password.RequireDigit = false;
            }).AddEntityFrameworkStores<AppDbContext>().AddDefaultTokenProviders();
          
            services.ConfigureApplicationCookie(options =>
            {
                options.Cookie.Name = "myCompanyAuth";
                options.Cookie.HttpOnly = true;
                options.LoginPath = "/account/login";
                options.AccessDeniedPath = "/account/accessdenied";
                options.SlidingExpiration = true;
            });

            services.AddControllersWithViews()
             .SetCompatibilityVersion(CompatibilityVersion.Version_3_0).AddSessionStateTempDataProvider();

            services.AddDbContext<RecommendationSiteContext>(options =>
                    options.UseSqlServer(Configuration.GetConnectionString("RecommendationSiteContext")));
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            //else
            //{
            //    app.UseExceptionHandler("/Home/Error");
            //    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
            //    app.UseHsts();
            //}

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseRouting();
            app.UseCookiePolicy();
            app.UseAuthentication();
            app.UseAuthorization();

            /*var defaultCulture = new CultureInfo("en-US");
            var localizationOptions = new RequestLocalizationOptions
            {
                DefaultRequestCulture = new RequestCulture(defaultCulture),
                SupportedCultures = new List<CultureInfo> { defaultCulture },
                SupportedUICultures = new List<CultureInfo> { defaultCulture },
            };

            app.UseRequestLocalization(localizationOptions);

            var ui = System.Globalization.CultureInfo.CurrentUICulture;*/

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

我是一个新手程序员，我对一些事情感到困惑，也许有人知道原因是什么？

我搜索了所有的论坛，并尝试了许多不同的变体。