Application is running inside IIS process but is not configured to use IIS server .NET Core 3.0

I also came across this issue while following the documentation https://learn.microsoft.com/en-us/aspnet/core/migration/22-to-30?view=aspnetcore-3.0&tabs=visual-studio

For your case I have checked and the code below will work, with the call to webBuilder.UseKestrel() removed.

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