Getting "Invalid route action" when upgrading Laravel from 5.0.33 to 5.1 LTS

Question

Here is my composer.json

{
    "name": "laravel/laravel",
    "description": "The Laravel Framework.",
    "keywords": ["framework", "laravel"],
    "license": "MIT",
    "type": "project",
    "require": {
        "laravel/framework": "5.1.*",
        "illuminate/html": "5.*",
        "lucadegasperi/oauth2-server-laravel": "~4.0"
        },
        "require-dev": {
            "phpunit/phpunit": "~4.0",
            "phpspec/phpspec": "~2.1",
        "laracasts/generators": "^1.1"
            },
            "autoload": {
                "classmap": [
                "database"
                ],
                "psr-4": {
                    "App\\": "app/"
                }
                },
                "autoload-dev": {
                    "classmap": [
                    "tests/TestCase.php"
                    ]
                    },
                    "scripts": {
                        "post-install-cmd": [
                        "php artisan clear-compiled",
                        "php artisan optimize"
                        ],
                        "post-update-cmd": [
                        "php artisan clear-compiled",
                        "php artisan optimize"
                        ],
                        "post-create-project-cmd": [
                        "php -r \"copy('.env.example', '.env');\"",
                        "php artisan key:generate"
                        ]
                        },
                        "config": {
                            "preferred-install": "dist"
                        }
                    }

When I run composer update command and follow that article

http://laravel.com/docs/master/upgrade

I get this error,

Invalid route action: [App\Http\Controllers\Auth\AuthController]

I searched everywhere but did not find a solution

UnexpectedValueException in Route.php line 624:
Invalid route action: [App\Http\Controllers\Auth\AuthController]
in Route.php line 624
at Route->parseAction(array('uses' => 'App\Http\Controllers\Auth\AuthController', 'controller' => 'App\Http\Controllers\Auth\AuthController')) in Route.php line 107
at Route->__construct(array('GET', 'HEAD'), 'login', array('uses' => 'App\Http\Controllers\Auth\AuthController', 'controller' => 'App\Http\Controllers\Auth\AuthController')) in Router.php line 518
at Router->newRoute(array('GET', 'HEAD'), 'login', array('uses' => 'App\Http\Controllers\Auth\AuthController', 'controller' => 'App\Http\Controllers\Auth\AuthController')) in Router.php line 494
at Router->createRoute(array('GET', 'HEAD'), 'login', 'Auth\AuthController') in Router.php line 472
at Router->addRoute(array('GET', 'HEAD'), 'login', 'Auth\AuthController') in Router.php line 132
at Router->get('login', 'Auth\AuthController') in Facade.php line 213
at Facade::__callStatic('get', array('login', 'Auth\AuthController')) in routes.php line 16
at Route::get('login', 'Auth\AuthController') in routes.php line 16
at require('C:\wamp\www\xgame\Web\xgame-app\app\Http\routes.php') in RouteServiceProvider.php line 40
at RouteServiceProvider->App\Providers\{closure}(object(Router))
at call_user_func(object(Closure), object(Router)) in Router.php line 350
at Router->group(array('namespace' => 'App\Http\Controllers'), object(Closure)) in RouteServiceProvider.php line 41
at RouteServiceProvider->map(object(Router))
at call_user_func_array(array(object(RouteServiceProvider), 'map'), array(object(Router))) in Container.php line 502
at Container->call(array(object(RouteServiceProvider), 'map')) in RouteServiceProvider.php line 68
at RouteServiceProvider->loadRoutes() in RouteServiceProvider.php line 30
at RouteServiceProvider->boot(object(Router)) in RouteServiceProvider.php line 25
at RouteServiceProvider->boot(object(Router))
at call_user_func_array(array(object(RouteServiceProvider), 'boot'), array(object(Router))) in Container.php line 502
at Container->call(array(object(RouteServiceProvider), 'boot')) in Application.php line 734
at Application->bootProvider(object(RouteServiceProvider)) in Application.php line 717
at Application->Illuminate\Foundation\{closure}(object(RouteServiceProvider), '19')
at array_walk(array(object(EventServiceProvider), object(RoutingServiceProvider), object(AuthServiceProvider), object(ControllerServiceProvider), object(CookieServiceProvider), object(DatabaseServiceProvider), object(EncryptionServiceProvider), object(FilesystemServiceProvider), object(FormRequestServiceProvider), object(FoundationServiceProvider), object(PaginationServiceProvider), object(SessionServiceProvider), object(ValidationServiceProvider), object(ViewServiceProvider), object(GeneratorsServiceProvider), object(AppServiceProvider), object(BusServiceProvider), object(ConfigServiceProvider), object(EventServiceProvider), object(RouteServiceProvider), object(FluentStorageServiceProvider), object(OAuth2ServerServiceProvider), object(BusServiceProvider)), object(Closure)) in Application.php line 718
at Application->boot() in BootProviders.php line 17
at BootProviders->bootstrap(object(Application)) in Application.php line 203
at Application->bootstrapWith(array('Illuminate\Foundation\Bootstrap\DetectEnvironment', 'Illuminate\Foundation\Bootstrap\LoadConfiguration', 'Illuminate\Foundation\Bootstrap\ConfigureLogging', 'Illuminate\Foundation\Bootstrap\HandleExceptions', 'Illuminate\Foundation\Bootstrap\RegisterFacades', 'Illuminate\Foundation\Bootstrap\RegisterProviders', 'Illuminate\Foundation\Bootstrap\BootProviders')) in Kernel.php line 223
at Kernel->bootstrap() in Kernel.php line 118
at Kernel->sendRequestThroughRouter(object(Request)) in Kernel.php line 88
at Kernel->handle(object(Request)) in index.php line 53
at require_once('C:\wamp\www\xgame\Web\xgame-app\public\index.php') in server.php line 21

By the way, I'm using Lucadegasperi library for integerating oAuth2 functionality with Laravel.

https://github.com/lucadegasperi/oauth2-server-laravel

Solution

The problem was caused by a route which is not compatible with the new version of Laravel 5.1

Route::get('login', 'Auth\AuthController');