How can customize Asp.net Identity 2 username already taken validation message?

Question

How can i customize Asp.net Identity 2 username already taken validation message(Name XYZ is already taken.)? Thanks

Answer 1

It can be done much easier than the accepted answer.

Add a class and inherit it from IdentityErrorDescriber

public class AppErrorDescriber : IdentityErrorDescriber
    {
        public override IdentityError DuplicateUserName(string userName)
        {
            var error = base.DuplicateUserName(userName);
            error.Description = "This email address has already been registered. Please log in.";
            return error;
        }
    }

Now use the new class in your Startup.cs and that's it.

services.AddDefaultIdentity(options => ... )
                .AddErrorDescriber();