How to customize ASP.NET Identity Core Username to allow special characters and space

Question

I have changed my Register Action Method to accept user Name instead of Email.

if (ModelState.IsValid)
{
    var user = new ApplicationUser          


        

Answer 1

So cloudikka's answer had it right. I'll just add explicitly (cloudikka's link explained it as well) that you need to list ALL the characters you want to allow (not just the whitespace or special characters), like this:

services.AddIdentity(options => {
    options.User.AllowedUserNameCharacters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+/ ";
});

and NOT this options.User.AllowedUserNameCharacters = " "; which means 'only whitespace characters allowed'. (I reckon this was Babar's problem.)