CannotUnloadAppDomainException when starting ASP.NET 5 website

Hello! I am new in ASP.NET 5 and trying to make a website with it, but I've got several problems.

I worked with .NET Clr and Entity Framework 6, but now I design to change EF to 7 and framework to CoreCLR (because I can't do migrations - enable-migration wasn't recognized). When I change my project.json,  do dnu restore, install CoreCLR using dnvm... and faced with error:

When I trying to run website in IIS Express, I face this error:

 System.CannotUnloadAppDomainException: Failed to unload the application domain. (Exception from HRESULT: 0x80131015)

Stack trace:

[CannotUnloadAppDomainException: Error while unloading the application domain. (Exception from HRESULT: 0x80131015)]
    System.Web.HttpRuntime.HostingInit (HostingEnvironmentFlags hostingFlags, PolicyLevel policyLevel, Exception appDomainCreationException) +303

[HttpException (0x80004005): Failed to unload the application domain. (Exception from HRESULT: 0x80131015)]
    System.Web.HttpRuntime.FirstRequestInit (HttpContext context) +9923088
    System.Web.HttpRuntime.EnsureFirstRequestInit (HttpContext context) +90
    System.Web.HttpRuntime.ProcessRequestNotificationPrivate (IIS7WorkerRequest wr, HttpContext context) +261

I use CoreCLR. My solution contains two projects: Domain (Models) and Stomatology (it's ASP.NET 5 website).

Project.json of "Domain" project

{"version": "1.0.0-*","description": "Domain Class Library","authors": [ "Garrus" ],"tags": [ "" ],"projectUrl": "","licenseUrl": "","dependencies": {"EntityFramework.Commands": "7.0.0-rc1-final","EntityFramework.Core": "7.0.0-beta8","EntityFramework.SqlServer": "7.0.0-beta8","Microsoft.CSharp": "4.0.0-beta-23019","System.Linq": "4.0.0-beta-23019","System.Runtime": "4.0.21-beta-23225","System.Threading": "4.0.10-beta-23019"
	},"frameworks": {"dnxcore50": {}
    }
}

and for "Stomatology":

{"webroot": "wwwroot","version": "1.0.0-*","dependencies": {"AutoMapper": "4.1.1","Domain": "1.0.0-*","Microsoft.AspNet.Html.Abstractions": "1.0.0-beta7","Microsoft.AspNet.Mvc": "6.0.0-beta7","Microsoft.AspNet.Mvc.TagHelpers": "6.0.0-beta7","Microsoft.AspNet.Server.IIS": "1.0.0-beta7","Microsoft.AspNet.Server.WebListener": "1.0.0-beta7","Microsoft.AspNet.StaticFiles": "1.0.0-beta7","EntityFramework.Core": "7.0.0-beta8","EntityFramework.SqlServer": "7.0.0-beta8","Microsoft.Framework.Configuration.Json": "1.0.0-beta8"
	},"commands": {"web": "Microsoft.AspNet.Hosting --config hosting.ini"
    },"frameworks": {"dnxcore50": {}
    },"publishExclude": ["node_modules","bower_components","**.xproj","**.user","**.vspscc"
    ],"exclude": ["wwwroot","node_modules","bower_components"
    ]
}

Here is my DNVM LIST:

Active Version         Runtime Architecture Location                                Alias
------ -------         ------- ------------ --------                                -----
       1.0.0-rc1-final clr     x86          C:\Users\Garrus.GARRUS-PC\.dnx\runtimes default
  *    1.0.0-rc1-final coreclr x86          C:\Users\Garrus.GARRUS-PC\.dnx\runtimes coreclr

It's not important, what the specifically code in my Startup.exe - I faced this error every time (In case startup.cs has no functions too). 

using Microsoft.Data.Entity;
using Microsoft.Framework.Configuration;
using Microsoft.Framework.Configuration.Json;

using Microsoft.AspNet.Builder;
using Microsoft.Framework.DependencyInjection;

using Domain.Abstract;
using Domain.Concrete;
using Domain.Models;

using System.Diagnostics;
using Microsoft.AspNet.Hosting;
using Microsoft.Dnx.Runtime;

namespace Stomatology
{
    public class Startup
    {
		IRepository repository
		IConfigurationRoot Configuration;

		public Startup(IHostingEnvironment env, IApplicationEnvironment appEnv)
		{
			var builder = new ConfigurationBuilder()
				.SetBasePath(appEnv.ApplicationBasePath)
				.AddJsonFile("config.json")
				.AddEnvironmentVariables();

			Configuration = builder.Build();
		}

		public void ConfigureServices(IServiceCollection services)
                {
			services.AddMvc();
			repository = new EFRepository();
			services.AddInstance<IRepository>(repository);

			services.AddEntityFramework()
				.AddSqlServer()
				.AddDbContext<DatabaseContext>(options =>
				{				              options.UseSqlServer(Configuration["Data:StomatologyLocalConnection:ConnectionString"]);
				});
		}

		public void Configure(IApplicationBuilder app)
                {
			app.UseMvc();           //<- Also, errors here. IApplicationBuilder is defined in assembly,
                                                //   which has no reference
			app.UseStaticFiles();

		}

		
    }
}

I think, I broke my project. Can anybody help me?
With best wishes, Alex.