System.MissingMethodException in Program.cs

Question

This exception just appeared in Program.cs when creating the host variable, I didn't update anything in Program.cs so I don't know why it appears. I've tried restarting VS and deleted bin and obj in all projects in the solution.

Exception:

Method not found: 'System.Collections.Generic.Dictionary`2 Microsoft.Extensions.Configuration.IConfigurationBuilder.get_Properties()'.

Program.cs:

using Microsoft.AspNetCore.Hosting;
using System.IO;

namespace LC.Smokers
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var host = new WebHostBuilder()
                .UseKestrel()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseIISIntegration()
                .UseStartup<Startup>()
                .UseApplicationInsights()
                .Build();

            host.Run();
        }
    }
}

Startup.cs:

public class Startup
{
    public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddEnvironmentVariables();
        Configuration = builder.Build();
    }

    public IConfigurationRoot Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddLocalization(options => options.ResourcesPath = "Resources");

        services.AddSingleton<IActionContextAccessor, Models.ActionContextAccessor>();
        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
        services.AddSingleton<AppHelper>();
        services.AddTransient<SessionHelper>();

        services.AddDistributedMemoryCache();

        services.AddSession(options =>
        {
            options.Cookie.Name = ".Smokers.Session";
            options.IdleTimeout = TimeSpan.FromHours(2);
        });

        services.AddMvc()
            .AddViewLocalization(Microsoft.AspNetCore.Mvc.Razor.LanguageViewLocationExpanderFormat.Suffix)
            .AddDataAnnotationsLocalization();
    }

    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("/Shop/Error");
        }

        List<CultureInfo> supportedCultures = new List<CultureInfo>
        {
            new CultureInfo("no-NB"),
            new CultureInfo("en-US")
        };

        app.UseRequestLocalization(new RequestLocalizationOptions
        {
            DefaultRequestCulture = new RequestCulture("no-NB"),
            SupportedCultures = supportedCultures,
            SupportedUICultures = supportedCultures
        });

        app.UseSession();
        app.UseStaticFiles();

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

Answer 1

Turns out it was an issue with the Microsoft.AspNetCore.Session package that was using version 2.0.0 and the rest of the project is using 2.0.0 preview 2 final.

I downgraded the package and it worked.