Cannot create database migration on EF Core but It can when you ask to EnsureCreate database

I am trying to inject some repository to a service and some services to a controller but I am using the DbContext is an assembly that is not the startup project but oddily when i try to call to create a migration it tells me this design is not allowed but if I call the EnsureCreated() method it allows me to create the database… what could be happening

the error
Microsoft.EntityFrameworkCore.Design.OperationException: Unable to create an object of type ‘AppDbContext’. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
—> System.InvalidOperationException: Unable to resolve service for type ‘Microsoft.EntityFrameworkCore.DbContextOptions1[Repository.AppDbContext.AppDbContext]' while attempting to activate 'Repository.AppDbContext.AppDbContext'. at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters) at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetServiceOrCreateInstance(IServiceProvider provider, Type type) at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.<>c__DisplayClass13_4.<FindContextTypes>b__13() --- End of inner exception stack trace --- at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.<>c__DisplayClass13_4.<FindContextTypes>b__13() at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func1 factory)
at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)
at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl

here is the Service DI

public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContextPool<AppDbContext>(options =>
            {
                options.UseSqlServer(Configuration.GetConnectionString("ManagementServiceDb"));
            });
            services.AddIdentity<ApplicationUser, IdentityRole>(options => { 
                options.SignIn.RequireConfirmedAccount = false;
                options.User.RequireUniqueEmail = true;
            }).AddEntityFrameworkStores<AppDbContext>();
            services.AddScoped<IRepository<Producto>, ProductoRepositorio>();
            services.AddScoped<IRepository<RegistroActividad>, RegistroActividadRepositorio>();
            services.AddScoped<IRepository<ProductoRegistroActividad>, RegistroActividadesProductoRepositorio>();
            services.AddScoped<IRepository<TipoActividad>, TipoActividadRepositorio>();
            services.AddScoped<IRepository<ApplicationUser>, UsuarioRepositorio>();

            services.AddScoped<UnidadRepositorio>();

            services.AddScoped<ProductosServicios>();
            services.AddScoped<UsuarioServicio>();

            services.AddScoped<UnidadServicios>();

            services.AddControllersWithViews();
        }

>Solution :

Try to add a parameterless constructor in your DbContext class.

If that doesn’t work you might need to add a design time factory as described here.