NotSupportedException: No IUserTwoFactorTokenProvider named ‘Default’ is registered on GenerateEmailConfirmationTokenAync

In Startup.cs file you have modified services.AddDefaultIdentity to services.AddIdentity .

When calling GenerateEmailConfirmationTokenAync for example or any other identity function, if you receive the following error:

An unhandled exception occurred while processing the request.
NotSupportedException: No IUserTwoFactorTokenProvider<TUser> named ‘Default’ is registered. Microsoft.AspNetCore.Identity.UserManager<TUser>.GenerateUserTokenAsync(TUser user, string tokenProvider, string purpose)

Here is the fix : Add a AddDefaultTokenProviders() when adding identity() to services like this:

public void ConfigureServices(IServiceCollection services)
{ 
   services.AddIdentity(config =>
   {
   //config.Password.
    config.User.RequireUniqueEmail = true; //  email
    config.User.AllowedUserNameCharacters = "myexyzcodsecret";
    config.SignIn.RequireConfirmedEmail = true;
   }).AddEntityFrameworkStores<ApplicationDbContext>()
//the fix is below
.AddDefaultTokenProviders();
}

AddDefaultTokenProviders(); is the fix