title: InvalidOperationException Error
body: <p>Hello I'm getting this error:</p>
  
  <blockquote>
    <p>InvalidOperationException: Unable to resolve service for type
    'RegistrationMVC.Model.OurDbContext' while attempting to activate
    'RegistrationMVC.Controllers.HomeController'.</p>
  </blockquote>
  
  <p>I don't know what may cause it, can be something with dependencies?</p>
  
  <p>startup.cs</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Threading.Tasks;
  using Microsoft.AspNetCore.Builder;
  using Microsoft.AspNetCore.Hosting;
  using Microsoft.Extensions.Configuration;
  using Microsoft.Extensions.DependencyInjection;
  using Microsoft.Extensions.Logging;
  using WebApplicationCore.NetCore.DataAccess;
  using WebApplicationCore.NetCore.BusinessLogic;
  namespace WebApplicationCore.NetCore
      public class Startup
      {
          public Startup(IHostingEnvironment env)
          {
              var builder = new ConfigurationBuilder()
                  .SetBasePath(env.ContentRootPath)
                  .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                  .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                  .AddEnvironmentVariables();
              Configuration = builder.Build();
          }
  
      public IConfigurationRoot Configuration { get; }
  
      // This method gets called by the runtime. Use this method to add services to the container.
      public void ConfigureServices(IServiceCollection services)
      {
          // Add framework services.
          services.AddMvc();
  
          services.AddSingleton&lt;IConfigurationRoot&gt;(sp =&gt; { return this.Configuration; });
          services.AddScoped&lt;IContactDataAccess, ContactDataAccess&gt;();
          services.AddScoped&lt;IContactBusinessLogic, ContactBusinessLogic&gt;();
      }
  
      // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
      public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
      {
          loggerFactory.AddConsole(Configuration.GetSection("Logging"));
          loggerFactory.AddDebug();
  
          if (env.IsDevelopment())
          {
              app.UseDeveloperExceptionPage();
              app.UseBrowserLink();
          }
          else
          {
              app.UseExceptionHandler("/Home/Error");
          }
  
          app.UseStaticFiles();
  
          app.UseMvc(routes =&gt;
          {
              routes.MapRoute(
                  name: "default",
                  template: "{controller=Home}/{action=Index}/{id?}");
          });
      }
  }
  </code></pre>
  
  <p><a href="https://hastebin.com/ihocixasir.cs" rel="nofollow noreferrer" title="HomeController.cs">HomeController</a></p>
  
  <p><a href="https://hastebin.com/vobelenopu.cs" rel="nofollow noreferrer" title="OurDbContext">OurDbContext</a></p>