Startup.cs

using FBA2.Data;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Design;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;

namespace FBA2
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
       public class TemporaryDbContextFactory : IDesignTimeDbContextFactory<Database2Context>
        {
            public Database2Context CreateDbContext(string[] args)
            {
                var configuration = new ConfigurationBuilder()
                    .SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                    .Build();

                var builder = new DbContextOptionsBuilder<Database2Context>();

                var connectionString = configuration.GetConnectionString("fba2");

                builder.UseSqlServer(connectionString);

                /* Stop client query evaluation
                builder.ConfigureWarnings(w =>
                    w.Throw(RelationalEventId.QueryClientEvaluationWarning));
                */
                return new Database2Context(builder.Options);
            }
        }
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();


            services.AddDbContext<Database2Context>();

            services.AddControllersWithViews();
            
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}