Laravel 5.8 cannot generate api_token when new user register

In your user model add 'api_token' to your fillables

class User extends Authenticatable
{
    use Notifiable;

/**
 * The attributes that are mass assignable.
 *
 * @var array
 */
protected $fillable = [
    'name', 
    'email', 
    'password', 
    'api_token'
];