エラーログですが、見にくくて申し訳ないのですが
SQLSTATE[HY000]: General error: 2006 MySQL server has gone away at /home/当方のパス/public_html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/AbstractMySQLDriver.php:115, Doctrine\\DBAL\\Driver\\PDOException(code: HY000): SQLSTATE[HY000]: General error: 2006 MySQL server has gone away at /home/当方のパス/public_html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php:93, PDOException(code: HY000): SQLSTATE[HY000]: General error: 2006 MySQL server has gone away at /home/当方のパス/public_html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php:91)"} [GET, /html/当方のパス/product/product/new, 219.162.86.31, http://当方のドメイン.com/html/当方のパス/content/cache, Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36]
SQLSTATE[HY000]: General error: 2006 MySQL server has gone away (uncaught exception) at /home/当方のパス/public_html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/AbstractMySQLDriver.php line 115 {"exception":"[object] (Doctrine\\DBAL\\Exception\\DriverException(code: 0): An exception occurred while executing 'SELECT t0.id AS id1, t0.name AS name2, t0.rank AS rank3 FROM mtb_work t0 WHERE t0.id = ?' with params [1]:

と出ていました。
ちなみに、/app/cache/twig/production/defaultの中には、00～ffまでのフォルダが256個作成されている状態です。