[Bitrix\Main\DB\ConnectionException] 
Mysql connect error [localhost]: (2006) MySQL server has gone away (400)
/var/www/html/site.ru/bitrix/modules/main/lib/db/mysqliconnection.php:65
#0: Bitrix\Main\DB\MysqliConnection->connectInternal()
	/var/www/html/site.ru/bitrix/modules/main/lib/db/mysqliconnection.php:122
#1: Bitrix\Main\DB\MysqliConnection->queryInternal(string, NULL, NULL)
	/var/www/html/site.ru/bitrix/modules/main/lib/db/connection.php:330
#2: Bitrix\Main\DB\Connection->query(string, NULL, integer, integer)
	/var/www/html/site.ru/bitrix/modules/main/lib/db/connection.php:358
#3: Bitrix\Main\DB\Connection->queryScalar(string)
	/var/www/html/site.ru/bitrix/modules/main/lib/composite/internals/locker.php:25
#4: Bitrix\Main\Composite\Internals\Locker::lock(string)
	/var/www/html/site.ru/bitrix/modules/main/lib/composite/engine.php:475
#5: Bitrix\Main\Composite\Engine::processPageContent(string)
	/var/www/html/site.ru/bitrix/modules/main/lib/composite/engine.php:422
#6: Bitrix\Main\Composite\Engine::endBuffering(string, string)
	/var/www/html/site.ru/bitrix/modules/main/classes/general/main.php:3196
#7: CAllMain->EndBufferContent(string)
	/var/www/html/site.ru/bitrix/modules/main/classes/general/main.php:3140
#8: CAllMain->EndBufferContentMan()
	/var/www/html/site.ru/bitrix/modules/main/include/epilog_after.php:36
#9: require(string)
	/var/www/html/site.ru/bitrix/modules/main/include/epilog.php:3
#10: require_once(string)
	/var/www/html/site.ru/bitrix/footer.php:4
#11: require(string)
	/var/www/html/site.ru/catalog/index.php:556
#12: include_once(string)
	/var/www/html/site.ru/bitrix/modules/main/include/urlrewrite.php:159
#13: include_once(string)
	/var/www/html/site.ru/bitrix/urlrewrite.php:2