Laravel 5.5无法使用auth脚手架登录

我在安装auth脚手架并创建用于存储使用除用户名和密码以外的凭据的数据库之后，在我的应用程序上进行注册 - 登录功能 . 我已成功注册新帐户，存储到数据库中，并重定向到管理员页面 . 但是在注销后，我无法使用我创建的先前帐户登录，并显示如下错误消息 .

Error message that prevent login

我该怎么办？

这是我的：

web.php

Route::get('/', 'FrontController@home')->name('home');

Route::get('/login', 'FrontController@login')->name('login');

Auth::routes();

Route::get('/home', 'AdminController@index')->name('admin');

Route::get('/manual', 'ManualLoginController@manual')->name('manual');

Route::get('/logout', '\App\Http\Controllers\Auth\LoginController@logout')->name('logout');

LoginController.php

<?php

namespace App\Http\Controllers\Auth;

use Auth;
use Illuminate\Http\Request;
use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\AuthenticatesUsers;

class LoginController extends Controller
{

    use AuthenticatesUsers;

    /**
     * Where to redirect users after login.
     *
     * @var string
     */
    protected $redirectTo = '/home';

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest')->except('logout');
    }

    public function logout(Request $request) {
          Auth::logout();
          return redirect('/login');
    }

}

login.blade.php

<div class="container-fluid-full">         
    <div class="row-fluid">
        <div class="login-box">
            <div class="icons">
                <a href="/"><i class="halflings-icon home"></i></a>
                <a href="#"><i class="halflings-icon cog"></i></a>
            </div>
            <h2 style="font-family: 'Raleway'; font-weight: 800">Masuk sebagai administrator</h2>
            @if ($errors->any()) 
            <div class="alert alert-danger">
                <ul>
                    @foreach ($errors->all() as $error)
                        <li>{{ $error }}</li>
                    @endforeach
                </ul>
            </div>
            @endif
            <form class="form-horizontal" action="{{route('login')}}" method="POST">
                @csrf
                <fieldset>
                    <div class="input-prepend" title="Username">
                        <label for="username">{{ __('Username') }}</label>

                        <span class="add-on"><i class="halflings-icon user"></i></span>

                        <input class="input-large span10 form-control{{ $errors->has('username') ? ' is-invalid' : '' }}" name="username" id="username" type="text" placeholder="username" value="{{ old('username') }}" required autofocus/>

                        @if ($errors->has('username'))
                            <span class="invalid-feedback" role="alert">
                                <strong>{{ $errors->first('username') }}</strong>
                            </span>
                        @endif
                    </div>


                    <div class="clearfix"></div>

                    <div class="input-prepend" title="Password">
                        <label for="password">{{ __('Password') }}</label>

                        <span class="add-on"><i class="halflings-icon lock"></i></span>

                        <input class="input-large span10 form-control{{ $errors->has('password') ? ' is-invalid' : '' }}" name="password" id="password" type="password" placeholder="Password" required/>

                        @if ($errors->has('password'))
                            <span class="invalid-feedback" role="alert">
                                <strong>{{ $errors->first('password') }}</strong>
                            </span>
                        @endif
                    </div>

                    <div class="clearfix"></div>

                    <div class="button-login">  
                        <button type="submit" class="btn btn-primary"> {{ __('Login') }}
                        </button>
                    </div>
                    <div class="clearfix"></div>
                </fieldset>
            </form>
        </div><!--/span-->
    </div><!--/row-->
</div>

RegisterController.php

<?php

namespace App\Http\Controllers\Auth;

use App\User;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Facades\Validator;
use Illuminate\Foundation\Auth\RegistersUsers;

class RegisterController extends Controller
{

    use RegistersUsers;

    /**
     * Where to redirect users after registration.
     *
     * @var string
     */
    protected $redirectTo = '/home';

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest');
    }

    /**
     * Get a validator for an incoming registration request.
     *
     * @param  array  $data
     * @return \Illuminate\Contracts\Validation\Validator
     */
    protected function validator(array $data)
    {
        return Validator::make($data, [
            'username' => 'required|string|max:255|unique:users',
            'password' => 'required|string|min:4|confirmed',
        ]);
    }

    /**
     * Create a new user instance after a valid registration.
     *
     * @param  array  $data
     * @return \App\User
     */
    protected function create(array $data)
    {
        return User::create([
            'username' => $data['username'],
            'password' => Hash::make($data['password']),
        ]);
    }
}

FronController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

class FrontController extends Controller
{
    public function home () {
        return view ('home');
    }

    public function login () {
        return view ('login');
    }

}

AdminController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

class AdminController extends Controller
{
    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('auth');
    }

    /**
     * Show the application dashboard.
     *
     * @return \Illuminate\Http\Response
     */
    public function index()
    {
        return view('admin');
    }
}