InvalidOperationException: No service for type Microsoft.AspNetCore.Identity.UserManager has been registered error using ASP.NET Identity Server - asp.net-core

Question

I am trying to put all my data in one database, including business data and Identity data. So, I have run the migrations on my database and updated my DbContext.
I'm trying to modify my project from the New Project template for specified users in Blazor Web Assembly.
I run the app. It loads the home page. But, when I click Login, I receive the error:
An unhandled exception occurred while processing the request.
InvalidOperationException: No service for type
'Microsoft.AspNetCore.Identity.UserManager`1[MyProject.Server.Models.ApplicationUser]'
has been registered.
In my MyProject.Server Startup.cs file:
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<MyContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
services.AddDatabaseDeveloperPageExceptionFilter();
services.AddDefaultIdentity<ApplicationUser>(options => options.SignIn.RequireConfirmedAccount = false)
.AddRoles<IdentityRole>()
.AddDefaultTokenProviders()
.AddUserManager<UserManager<ApplicationUser>>()
.AddSignInManager<SignInManager<ApplicationUser>>()
.AddEntityFrameworkStores<MyContext>();
services.AddIdentityServer(
options =>
{
options.Events.RaiseErrorEvents = true;
options.Events.RaiseInformationEvents = true;
options.Events.RaiseFailureEvents = true;
options.Events.RaiseSuccessEvents = true;
}
)
.AddClientStore<ClientStore>()
.AddConfigurationStore<MyContext>(options =>
{
options.ConfigureDbContext = b => b.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
})
.AddOperationalStore<MyContext>(options =>
{
options.ConfigureDbContext = b => b.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
})
.AddApiAuthorization<ApplicationUser, MyContext>();
services.AddAuthentication().AddIdentityServerJwt();
services.AddControllersWithViews();
services.AddRazorPages();
}
There's nothing special in my ApplicationUser class:
public class ApplicationUser : IdentityUser
{
}
And in my _LoginPartial.cshtml:
#using Microsoft.AspNetCore.Identity
#using MyProject.Server.Models
#inject SignInManager<ApplicationUser> SignInManager
#inject UserManager<ApplicationUser> UserManager
I didn't think I was trying to do anything special. The main thing is I am using a customer DbContext that overrides OnModelCreating. That is why I need to define so much of the IdentityServer.

Answer 1

If you are using .Net core 5
add this :
services.AddIdentityCore<ApplicationUser>();
according to the source code here this will register UserManager<ApplicationUser>