cannot execute php artisan command [php fatal error[ - php

Question

I have a laravel project I installed the composer
and run
composer install
After that I executed the update command
composer update
on the project's root directory, and during the execution on the command
php artisan optimize
I got the error shown in the attached image.
When I try to execute any php artisan command I got the same error too.
Error lines
PHP Fatal error: Uncaught Error: Call to undefined method Illuminate\Support\Facades\Auth::check() in C:\xampp\htdocs\projectx\vendor\laravel\framework\src\Illuminate\Support\Facades\Facade.php:221
Stack trace:
#0 C:\xampp\htdocs\projectx\app\Exceptions\Handler.php(39): Illuminate\Support\Facades\Facade::__callStatic('check', Array)
#1 C:\xampp\htdocs\projectx\vendor\laravel\framework\src\Illuminate\Foundation\Bootstrap\HandleExceptions.php(81): App\Exceptions\Handler->report(Object(Symfony\Component\Debug\Exception\FatalThrowableError))
#2 [internal function]: Illuminate\Foundation\Bootstrap\HandleExceptions->handleException(Object(Symfony\Component\Debug\Exception\FatalThrowableError))
#3 {main}
thrown in C:\xampp\htdocs\projectx\vendor\laravel\framework\src\Illuminate\Support\Facades\Facade.php on line 221
PHP Fatal error: Uncaught Error: Call to undefined method Illuminate\Support\Facades\Auth::check() in C:\xampp\htdocs\projectx\vendor\laravel\framework\src\Illuminate\Support\Facades\Facade.php:221
Stack trace:
#0 C:\xampp\htdocs\projectx\app\Exceptions\Handler.php(39): Illuminate\Support\Facades\Facade::__callStatic('check', Array)
#1 C:\xampp\htdocs\projectx\vendor\laravel\framework\src\Illuminate\Foundation\Bootstrap\HandleExceptions.php(81): App\Exceptions\Handler->report(Object(Symfony\Component\Debug\Exception\FatalErrorException))
#2 C:\xampp\htdocs\projectx\vendor\laravel\framework\src\Illuminate\Foundation\Bootstrap\HandleExceptions.php(123): Illuminate\Foundation\Bootstrap\HandleExceptions->handleException(Object(Symfony\Component\Debug\Exception\FatalErrorException))
#3 [internal function]: Illuminate\Foundation\Bootstrap\HandleExceptions->handleShutdown()
#4 {main}
thrown in C:\xampp\htdocs\projectx\vendor\laravel\framework\src\Illuminate\Support\Facades\Facade.php on line 221

Answer 1

You could try to use the append_config() helper method in your environment app configuration file:
'providers' => append_config(array(
'LocalOnlyServiceProvider',
))

Answer 2

The command php artisan optimize has been remove in laravel 5.6
see more: https://laravel.com/docs/5.6/upgrade