Notice: Undefined property: DOMDocument::$documentElement in /home/www/shopware/vendor/symfony/dependency-injection/Loader/XmlFileLoader.php on line 579

Fatal error: Uncaught Error: Call to a member function getAttributeNS() on null in /home/www/shopware/vendor/symfony/dependency-injection/Loader/XmlFileLoader.php:579 Stack trace: #0 /home/www/shopware/vendor/symfony/config/Util/XmlUtils.php(83): Symfony\Component\DependencyInjection\Loader\XmlFileLoader->validateSchema(Object(DOMDocument), false) #1 /home/www/shopware/vendor/symfony/config/Util/XmlUtils.php(131): Symfony\Component\Config\Util\XmlUtils::parse('<?xml version="...', Array) #2 /home/www/shopware/vendor/symfony/dependency-injection/Loader/XmlFileLoader.php(384): Symfony\Component\Config\Util\XmlUtils::loadFile('/home/www/shopw...', Array) #3 /home/www/shopware/vendor/symfony/dependency-injection/Loader/XmlFileLoader.php(44): Symfony\Component\DependencyInjection\Loader\XmlFileLoader->parseFileToDOM('/home/www/shopw...') #4 /home/www/shopware/engine/Shopware/Kernel.php(644): Symfony\Component\DependencyInjection\Loader\XmlFileLoader->load('services.xml') #5 /home/www/shopware/engine/Shopware/Kernel.php(629): S in /home/www/shopware/vendor/symfony/dependency-injection/Loader/XmlFileLoader.php on line 579