[Bitrix\Main\DB\SqlQueryException] 
Mysql query error: (2006) MySQL server has gone away (400)
SELECT GET_LOCK("cf1178073f4fdf95c727967921f55687", 60)
LIMIT 0, 1

/home/bitrix/shared-student/bitrix/modules/main/lib/db/mysqliconnection.php:137
#0: Bitrix\Main\DB\MysqliConnection->queryInternal(string, NULL, NULL)
	/home/bitrix/shared-student/bitrix/modules/main/lib/db/connection.php:330
#1: Bitrix\Main\DB\Connection->query(string, NULL, integer, integer)
	/home/bitrix/shared-student/bitrix/modules/main/lib/db/connection.php:358
#2: Bitrix\Main\DB\Connection->queryScalar(string)
	/home/bitrix/shared-student/bitrix/modules/security/lib/session.php:114
#3: Bitrix\Security\SessionTable::lock(string, integer)
	/home/bitrix/shared-student/bitrix/modules/security/classes/general/session_db.php:52
#4: CSecuritySessionDB::read(string)
	
#5: session_start()
	/home/bitrix/shared-student/bitrix/modules/main/include.php:281
#6: require_once(string)
	/home/bitrix/shared-student/bitrix/modules/main/include/prolog_before.php:14
#7: require_once(string)
	/home/bitrix/shared-student/bitrix/modules/main/include/prolog.php:10
#8: require_once(string)
	/home/bitrix/shared-student/bitrix/header.php:1
#9: require(string)
	/home/bitrix/ext_www/studmarket.ru/catalog/index.php:2
#10: include_once(string)
	/home/bitrix/shared-student/bitrix/modules/main/include/urlrewrite.php:159
#11: include_once(string)
	/home/bitrix/shared-student/bitrix/urlrewrite.php:2