Program.cs

using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Serilog;

namespace RazorPageDemo
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var configuration = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json", false, true)
                .AddJsonFile("appsettings.Development.json", true, true)
                .Build();

            Log.Logger = new LoggerConfiguration()
                .ReadFrom.Configuration(configuration)
                .CreateLogger();
            try
            {

                CreateHostBuilder(args).Build().Run();
            }
            catch (Exception ex)
            {
                Log.Error(ex, "Host terminated unexpectedly");
                throw;
            }
            finally
            {
                Log.CloseAndFlush();
            }
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .UseSerilog()
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}