public void ConfigureServices(IServiceCollection services)
{
	services.AddTransient<IContactService, ContactService>();//<---------------
	services.AddMvc()
		.AddControllersAsServices() 
		.SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

	var connection = @".;Database=ContactDB;Trusted_Connection=True;";
	services.AddDbContext<ContactDBContext>(options => options.UseSqlServer(connection));

	services.AddSpaStaticFiles(configuration =>
	{
		configuration.RootPath = "ClientApp/build";
	});
}

public void ConfigureServices(IServiceCollection services)
{
	services.AddTransient<IContactService, ContactService>();//<---------------
	services.AddTransient<IShopService, ShopService>();//<---------------
	services.AddTransient<IDeliveryService, DeliveryService>();//<---------------

	services.AddMvc()
		.AddControllersAsServices()
		.SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

	var connection = @".;Database=ContactDB;Trusted_Connection=True;";
	services.AddDbContext<ContactDBContext>(options => options.UseSqlServer(connection));

	services.AddSpaStaticFiles(configuration =>
	{
		configuration.RootPath = "ClientApp/build";
	});
}

            <NavbarBrand tag={Link} to="/">Приложение</NavbarBrand>

import React from 'react';
import { Collapse, Container, Navbar, NavbarBrand, 
NavbarToggler, NavItem, NavLink } from 'reactstrap';
import { Link } from 'react-router-dom';
import './NavMenu.css';

export default class NavMenu extends React.Component {
  constructor (props) {
    super(props);

    this.toggle = this.toggle.bind(this);
    this.state = {
      isOpen: false
    };
  }
  toggle () {
    this.setState({
      isOpen: !this.state.isOpen
    });
  }
  render () {
    return (
      <header>
        <Navbar className="navbar-expand-sm navbar-toggleable-sm 
         border-bottom box-shadow mb-3" light >
          <Container>
            <NavbarBrand tag={Link} to="/">Приложение</NavbarBrand>
            <NavbarToggler onClick={this.toggle} className="mr-2" />
            <Collapse className="d-sm-inline-flex flex-sm-row-reverse" 
                      isOpen={this.state.isOpen} navbar>
              <ul className="navbar-nav flex-grow">
                <NavItem>
                   <NavLink tag={Link} className="text-dark" to="/contacts">Contact</NavLink>
                </NavItem>
              </ul>
            </Collapse>
          </Container>
        </Navbar>
      </header>
    );
  }
}