An error occurred while accessing the Microsoft.Extensions.Hosting services when do first migrations

I don't understand what wrong.I tried to make a simple crud in .net core mvc with a very simple model which has few fields.

These are my models:

    public class Employee    {        [Key] public int EmployeeId { get; set; }        [Required] public string FistName { get; set; }        [Required] public string LastName { get; set; }        public int PositionId { get; set; }        public virtual Position Position { get; set; }    }public class Position    {        [Key]        public int PositionId { get; set; }        public string PositionName { get; set; }        public ICollection<Employee> Employees { get; set; }    }

then I made app context:

public class EmployeeContext : DbContext{    public EmployeeContext(DbContextOptions<EmployeeContext> options)        : base(options)    {    }    public DbSet<Employee> Employees { get; set; }    public DbSet<Position> Positions { get; set; }    protected override void OnModelCreating(ModelBuilder modelBuilder)    {        modelBuilder.Entity<Employee>()            .HasOne(e => e.Position)            .WithMany()            .HasForeignKey(e => e.PositionId);    }}

and registered context in Startup.cs:

 public void ConfigureServices(IServiceCollection services)    {        services.Configure<CookiePolicyOptions>(options =>        {            // This lambda determines whether user consent for non-essential cookies is needed for a given request.            options.CheckConsentNeeded = context => true;            options.MinimumSameSitePolicy = SameSiteMode.None;        });        services.AddDbContext<EmployeeContext>(item =>item.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);                        }

may be need one more file code of .csproj and program.cs

<Project Sdk="Microsoft.NET.Sdk.Web"><PropertyGroup><TargetFramework>net461</TargetFramework><DebugType>full</DebugType></PropertyGroup><ItemGroup><PackageReference Include="Microsoft.AspNetCore" Version="2.2.0" /><PackageReference Include="Microsoft.AspNetCore.CookiePolicy" Version="2.2.8" /><PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.2.0" /><PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.2.0" /><PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.1.2" /><PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="3.1.2"><PrivateAssets>all</PrivateAssets><IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets></PackageReference><PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.1.2" /><PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer.Design" Version="1.1.6" /><PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.1.2"><PrivateAssets>all</PrivateAssets><IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets></PackageReference><PackageReference Include="Microsoft.Extensions.Logging.Configuration" Version="3.1.2" /><PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="3.1.1" /></ItemGroup></Project>public class Program    {        public static void Main(string[] args)        {            CreateWebHostBuilder(args).Build().Run();        }        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>            WebHost.CreateDefaultBuilder(args)                .UseStartup<Startup>();    }

then I tried to do first migrate, but I see a very strange errorAdd-Migration FirstInit -verbose

Using project 'Crud'.Using startup project 'Crud'.Build started...Build succeeded.C:\.nuget\packages\microsoft.entityframeworkcore.tools\3.1.2\tools\net461\win-x86\ef.exe migrations add FirstInit --json --verbose --no-color --prefix-output --assembly C:\source\repos\Crud\Crud\bin\Debug\net461\Crud.exe --startup-assembly C:\source\repos\Crud\Crud\bin\Debug\net461\Crud.exe --project-dir C:\source\repos\Crud\Crud\ --language C# --working-dir C:\source\repos\Crud --root-namespace CrudUsing assembly 'Crud'.Using startup assembly 'Crud'.Using application base 'C:\source\repos\Crud\Crud\bin\Debug\net461'.Using working directory 'C:\source\repos\Crud\Crud'.Using root namespace 'Crud'.Using project directory 'C:\source\repos\Crud\Crud\'.Using configuration file 'C:\source\repos\Crud\Crud\bin\Debug\net461\Crud.exe.config'.Using assembly 'Crud'.Using startup assembly 'Crud'.Using application base 'C:\source\repos\Crud\Crud\bin\Debug\net461'.Using working directory 'C:\source\repos\Crud\Crud'.Using root namespace 'Crud'.Using project directory 'C:\source\repos\Crud\Crud\'.Finding DbContext classes...Finding IDesignTimeDbContextFactory implementations...Finding application service provider...Finding Microsoft.Extensions.Hosting service provider...Using environment 'Development'.System.TypeLoadException: There is no implementation of the GetItem method in the type "Microsoft.AspNetCore.Mvc.Razor.Internal.FileProviderRazorProjectFileSystem" from assembly "Microsoft.AspNetCore.Mvc.Razor, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60".в Microsoft.Extensions.DependencyInjection.MvcRazorMvcCoreBuilderExtensions.AddRazorViewEngineServices(IServiceCollection services)в Microsoft.Extensions.DependencyInjection.MvcRazorMvcCoreBuilderExtensions.AddRazorViewEngine(IMvcCoreBuilder builder)в Microsoft.Extensions.DependencyInjection.MvcServiceCollectionExtensions.AddMvc(IServiceCollection services)в Crud.Startup.ConfigureServices(IServiceCollection services) в C:\source\repos\Crud\Crud\Startup.cs:строка 38--- End the stack trace from the previous location where the exception occurred ---в System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()в Microsoft.AspNetCore.Hosting.ConventionBasedStartup.ConfigureServices(IServiceCollection services)в Microsoft.AspNetCore.Hosting.Internal.WebHost.EnsureApplicationServices()в Microsoft.AspNetCore.Hosting.Internal.WebHost.Initialize()в Microsoft.AspNetCore.Hosting.WebHostBuilder.Build()An error occurred while accessing the Microsoft.Extensions.Hosting services. Continuing without the application service provider. Error: There is no implementation of the GetItem method in the type "Microsoft.AspNetCore.Mvc.Razor.Internal.FileProviderRazorProjectFileSystem" from assembly "Microsoft.AspNetCore.Mvc.Razor, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60".No application service provider was found.Finding DbContext classes in the project...Found DbContext 'EmployeeContext'.Microsoft.EntityFrameworkCore.Design.OperationException: Unable to create an object of type 'EmployeeContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728 ---> System.MissingMethodException:There are no parameterless constructors defined for this object..в System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)в System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)в System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)в System.Activator.CreateInstance(Type type, Boolean nonPublic)в System.Activator.CreateInstance(Type type)в Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.<>c__DisplayClass13_3.<FindContextTypes>b__13()   --- End trace of internal exception stack ---в Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.<>c__DisplayClass13_3.<FindContextTypes>b__13()в Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func`1 factory)в Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)в Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType)в Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType)в Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()в Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()в Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)Unable to create an object of type 'EmployeeContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

What's wrong with these 3 lines?