Configure Microsoft.AspNet.Identity to allow email address as username

Question

You can allow this by plugging in your own UserValidator on the UserManager, or just by turning it off on the default implementation:

UserManager.UserValidator = new UserValidator<TUser>(UserManager) { AllowOnlyAlphanumericUserNames = false }

The C# version of this (in App_Code\IdentityModels.cs) is

public UserManager()
        : base(new UserStore<ApplicationUser>(new ApplicationDbContext()))
    {
        UserValidator = new UserValidator<ApplicationUser>(this) { AllowOnlyAlphanumericUserNames = false };
    }

In my case, running in VS 2013 C#, MVC 5.2.2, using ASP.NET Identity 2.0, the solution was to update the ApplicationUserManager constructor inside App_Start\IdentityConfig.cs like so:

public ApplicationUserManager(IUserStore<ApplicationUser> store)
        : base(store)
    {
        this.UserValidator = new UserValidator<ApplicationUser>(this) { AllowOnlyAlphanumericUserNames = false };
    }

I had the same problem, when I tried to change the code for make the UserName was the real name of the person and not the email the system show me the same error message "User name ABC DEF is invalid, can only contain letters or digits." I solved the problem adding the space character (In my case at the end) to AllowedUserNameCharacters.

Im using Asp.Net Core 2.2 and VS2017

This is my code

Go to Startup.cs and edit or add the line under "//user settings":

        services.AddDbContext<ApplicationDbContext>(options =>
            options.UseMySql(Configuration.GetConnectionString("DefaultConnection")));

        services.AddIdentity<ApplicationUser, ApplicationRole>()
            .AddEntityFrameworkStores<ApplicationDbContext>()
            .AddDefaultTokenProviders();

        services.Configure<IdentityOptions>(options =>
        {
            // Password settings.
            options.Password.RequireDigit = true;
            options.Password.RequireLowercase = true;
            options.Password.RequireNonAlphanumeric = true;
            options.Password.RequireUppercase = true;
            options.Password.RequiredLength = 6;
            options.Password.RequiredUniqueChars = 1;

            // Lockout settings.
            options.Lockout.DefaultLockoutTimeSpan = TimeSpan.FromMinutes(5);
            options.Lockout.MaxFailedAccessAttempts = 5;
            options.Lockout.AllowedForNewUsers = true;


            // User settings.
            options.User.AllowedUserNameCharacters =
                "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+ ";
            options.User.RequireUniqueEmail = false;
        });

        services.ConfigureApplicationCookie(options =>

For people on AspNet.Identity.Core 2.1 and up, these validators in the UserManager are readonly. Email addresses as usernames are allowed by default but if you need further customisation of the characters in your usernames, you can do so in Startup.cs like this:

public void ConfigureServices(IServiceCollection services)
{
    services.AddIdentity<ApplicationUser, IdentityRole>(options => {
        options.User.AllowedUserNameCharacters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+/";
    });

    // ... etc
}

(I needed a '/' for legacy reasons.)

If you are using ASP.Net webforms and are trying to accomplish this, simply open up your IdentityModels.vb/cs file and under Public Class UserManager, have it look as so:

Public Class UserManager
Inherits UserManager(Of ApplicationUser)

Public Sub New()
    MyBase.New(New UserStore(Of ApplicationUser)(New ApplicationDbContext()))
    Users = store
    UserValidator = New UserValidator(Of ApplicationUser)(Me) With {.AllowOnlyAlphanumericUserNames = False}
End Sub

Public Property Users() As IUserStore(Of ApplicationUser)
    Get
        Return m_Users
    End Get
    Private Set(value As IUserStore(Of ApplicationUser))
        m_Users = value
    End Set
End Property
Private m_Users As IUserStore(Of ApplicationUser)

End Class

Since coding my own ApplicationUserManager : UserManager class didn't work for me (maybe bc I use Razor Pages, not MVC), here's another solution: In Startup.cs in CofigureServices() you can configure Identity Options, for example:

services.Configure<IdentityOptions>(options =>
{
  options.User.AllowedUserNameCharacters = 
  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ@";
  options.User.RequireUniqueEmail = true;
});

More on this topic in Microsoft docs: https://docs.microsoft.com/de-de/aspnet/core/security/authentication/identity-configuration?view=aspnetcore-2.2