Fatal error: Uncaught RuntimeException: PHP's json extension is required to use Monolog's NormalizerFormatter in /var/www/magento2/vendor/monolog/monolog/src/Monolog/Formatter/NormalizerFormatter.php:34 Stack trace: #0 /var/www/magento2/vendor/monolog/monolog/src/Monolog/Formatter/LineFormatter.php(42): Monolog\Formatter\NormalizerFormatter->__construct(NULL) #1 /var/www/magento2/lib/internal/Magento/Framework/Logger/Handler/Base.php(50): Monolog\Formatter\LineFormatter->__construct(NULL, NULL, true) #2 /var/www/magento2/lib/internal/Magento/Framework/ObjectManager/Factory/AbstractFactory.php(111): Magento\Framework\Logger\Handler\Base->__construct(Object(Magento\Framework\Filesystem\Driver\File), NULL, NULL) #3 /var/www/magento2/lib/internal/Magento/Framework/ObjectManager/Factory/Compiled.php(108): Magento\Framework\ObjectManager\Factory\AbstractFactory->createObject('Mirasvit\\CacheW...', Array) #4 /var/www/magento2/lib/internal/Magento/Framework/ObjectManager/Factory/Compiled.php(150): Magento\Framework\ObjectManager\ in /var/www/magento2/vendor/monolog/monolog/src/Monolog/Formatter/NormalizerFormatter.php on line 34