Error Message are not being sent to Blade. Laravel 5.2.12

I am using Laravel 5.2.12

I have a request class like below.

class RegisterRequest extends Request
{
    public function authorize()
    {
        return true;
    }

    public function rules()
    {
        return [
            'UserName'      =>  'required|min:5|max:50',
            'Password'      =>  'required|confirmed|min:5|max:100',
        ];
    }

    public function response(array $errors){
        print_r($errors);
        return \Redirect::back()->withErrors($errors)->withInput();
    }
}

This request class is being used to validate the data during registration in the inbuilt template of Laravel. Below are the methods

public function postRegister(RegisterRequest $request)
//            **Check here** ^^^^^^^^^^^^^^^
{
    return $this->register($request);
}

We can find the path for this method below.

\vendor\laravel\framework\src\Illuminate\Foundation\Auth\RegistersUsers.php

Below is the code written in Register page.

@if (count($errors) > 0)
    <div class="alert alert-danger">
        <strong>Whoops!</strong> There were some problems with your input.<br><br>
        <ul>
            @foreach ($errors->all() as $error)
                <li>{{ $error }}</li>
            @endforeach
        </ul>
    </div>
@endif

What's the problem ?

Error messages are not displaying in register Blade.

What have I tried so far ?

In the request class, there is below method.

public function response(array $errors){
    print_r($errors);
    //die();
    return \Redirect::back()->withErrors($errors)->withInput();
}

Although it prints when I enable die() but it never sends the error message in blade.

via Chebli Mohamed