Uncaught Error: Class 'Symfony\Component\Config\Resource\ClassExistenceResource' not found

Question

I added the Symfony Dependency injection container (composer require symfony/dependency-injection): https://symfony.com/doc/current/components/dependency_injection.html

Run the: composer dump-autoload -o to reorganize classes (/www/vendor/composer/autoload_classmap.php file is empty after installing new libraries via composer).

have this running in my init.php file:

use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Reference;
use MyApp\Core\App; 
use MyApp\Core\Database; 
use MyApp\Models\SystemUser; 
use MyApp\Models\Customer; 
use MyApp\Core\Log;
$container = new ContainerBuilder();

    $container->autowire( Log::class );
    $container->autowire( Database::class );
    $container->autowire( SystemUser::class );
    $container->autowire( Customer::class );
    $container->autowire( App::class )
        ->setPublic( true );

    $container->compile();

    $app = $container->get( App::class );

and breaks on compile().

What am I missing?

Cannot find any lead to resolve this problem.

What am I doing wrong?

PHP Fatal error:  Uncaught Error: Class 'Symfony\Component\Config\Resource\ClassExistenceResource' not found in /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php:385
Stack trace:
#0 /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(225): Symfony\Component\DependencyInjection\Compiler\AutowirePass->createTypeNotFoundMessage(Object(Symfony\Component\DependencyInjection\TypedReference), 'argument "$db" ...')
#1 /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(256): Symfony\Component\DependencyInjection\Compiler\AutowirePass->Symfony\Component\DependencyInjection\Compiler\{closure}()
#2 /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(165): Symfony\Component\DependencyInjection\Compiler\AutowirePass->autowireMethod(Object(ReflectionMethod), Array)
#3 /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(123): Symfony\Component\DependencyInjection\Compiler\AutowirePass->autowireCalls(Object(ReflectionClass), true)
#4 /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(71): Symfony\Component\DependencyInjection\Compiler\AutowirePass->doProcessValue(Object(Symfony\Component\DependencyInjection\Definition), true)
#5 /www/vendor/symfony/dependency-injection/Compiler/AbstractRecursivePass.php(82): Symfony\Component\DependencyInjection\Compiler\AutowirePass->processValue(Object(Symfony\Component\DependencyInjection\Definition), true)
#6 /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(100): Symfony\Component\DependencyInjection\Compiler\AbstractRecursivePass->processValue(Array, true)
#7 /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(71): Symfony\Component\DependencyInjection\Compiler\AutowirePass->doProcessValue(Array, true)
#8 /www/vendor/symfony/dependency-injection/Compiler/AbstractRecursivePass.php(46): Symfony\Component\DependencyInjection\Compiler\AutowirePass->processValue(Array, true)
#9 /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(52): Symfony\Component\DependencyInjection\Compiler\AbstractRecursivePass->process(Object(Symfony\Component\DependencyInjection\ContainerBuilder))
#10 /www/vendor/symfony/dependency-injection/Compiler/Compiler.php(95): Symfony\Component\DependencyInjection\Compiler\AutowirePass->process(Object(Symfony\Component\DependencyInjection\ContainerBuilder))
#11 /www/vendor/symfony/dependency-injection/ContainerBuilder.php(750): Symfony\Component\DependencyInjection\Compiler\Compiler->compile(Object(Symfony\Component\DependencyInjection\ContainerBuilder))
#12 /www/myapp/init.php(50): Symfony\Component\DependencyInjection\ContainerBuilder->compile()
#13 /www/public/index.php(10): require_once('/www/myapp/...')
#14 {main}
  thrown in /www/vendor/symfony/dependency-injection/Compiler/AutowirePass.php on line 385

composer.json

{
    "name": "potato/www",

    "authors": [
        {
            "name": "potato potato",
            "email": "[email protected]"
        }
    ],

    "require": {
        "monolog/monolog": "^1.24",
        "filp/whoops": "^2.3",
        "symfony/dependency-injection": "^4.2"
    }, 

    "autoload":{
        "psr-4": {
            "MyApp\\": "myapp"
        }
    },
    "require-dev": {
        "squizlabs/php_codesniffer": "^3.3"
    }
}

Answer 1

Reason seems to be pretty simple: you have required symfony/dependency-injection but Symfony\Component\Config\Resource\ClassExistenceResource obviously belongs to symfony/config. If you will review dependencies of symfony/dependency-injection you will see that it requires symfony/config only as dev dependency. Hence simple inclusion of symfony/config should fix the issue.

Reason of this error is another question and probably should be reported to Symfony developers.