[Bitrix\Main\DB\SqlQueryException] 
Mysql query error: (2006) MySQL server has gone away (400)

				SELECT FROM_MODULE_ID, MESSAGE_ID, SORT, TO_MODULE_ID, TO_PATH,
					TO_CLASS, TO_METHOD, TO_METHOD_ARG, VERSION
				FROM b_module_to_module m2m
					INNER JOIN b_module m ON (m2m.TO_MODULE_ID = m.ID)
				ORDER BY SORT
			
/home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php:137
#0: Bitrix\Main\DB\MysqliConnection->queryInternal(string, array, NULL)
	/home/bitrix/www/bitrix/modules/main/lib/db/connection.php:330
#1: Bitrix\Main\DB\Connection->query(string)
	/home/bitrix/www/bitrix/modules/main/lib/eventmanager.php:230
#2: Bitrix\Main\EventManager->loadEventHandlers()
	/home/bitrix/www/bitrix/modules/main/lib/eventmanager.php:333
#3: Bitrix\Main\EventManager->findEventHandlers(string, string, NULL)
	/home/bitrix/www/bitrix/modules/main/lib/eventmanager.php:368
#4: Bitrix\Main\EventManager->send(object)
	/home/bitrix/www/bitrix/modules/main/lib/event.php:142
#5: Bitrix\Main\Event->send()
	/home/bitrix/www/bitrix/modules/main/classes/general/usertype.php:1287
#6: CUserTypeManager->getEntityList()
	/home/bitrix/www/bitrix/modules/main/lib/orm/entity.php:298
#7: Bitrix\Main\ORM\Entity->postInitialize()
	/home/bitrix/www/bitrix/modules/main/lib/orm/entity.php:121
#8: Bitrix\Main\ORM\Entity::getInstanceDirect(string)
	/home/bitrix/www/bitrix/modules/main/lib/orm/entity.php:104
#9: Bitrix\Main\ORM\Entity::getInstance(string)
	/home/bitrix/www/bitrix/modules/main/lib/orm/data/datamanager.php:81
#10: Bitrix\Main\ORM\Data\DataManager::getEntity()
	/home/bitrix/www/bitrix/modules/security/lib/session.php:110
#11: Bitrix\Security\SessionTable::lock(string, integer)
	/home/bitrix/www/bitrix/modules/security/classes/general/session_db.php:52
#12: CSecuritySessionDB::read(string)
	/home/bitrix/www/bitrix/modules/security/classes/general/session_handler.php:23
#13: CSecuritySessionHandler->read(string)
	
#14: session_start()
	/home/bitrix/www/bitrix/modules/main/include.php:288
#15: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog_before.php:14
#16: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog.php:10
#17: require_once(string)
	/home/bitrix/www/bitrix/header.php:1
#18: require(string)
	/home/bitrix/ext_www/s2/index.php:2
#19: include_once(string)
	/home/bitrix/www/bitrix/modules/main/include/urlrewrite.php:159
#20: include_once(string)
	/home/bitrix/www/bitrix/urlrewrite.php:2