[Bitrix\Main\DB\SqlQueryException] 
Mysql query error: (2006) MySQL server has gone away (400)
SELECT 
	`security_session`.`SESSION_DATA` AS `SESSION_DATA`
FROM `b_sec_session` `security_session` 

WHERE `security_session`.`SESSION_ID` = '4fQbT0qTuZNm87njdgFoPR3XDXNyLEnH'
LIMIT 0, 1

/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:329
#1: Bitrix\Main\DB\Connection->query(string)
	/home/bitrix/www/bitrix/modules/main/lib/entity/query.php:1873
#2: Bitrix\Main\Entity\Query->query(string)
	/home/bitrix/www/bitrix/modules/main/lib/entity/query.php:460
#3: Bitrix\Main\Entity\Query->exec()
	/home/bitrix/www/bitrix/modules/main/lib/entity/datamanager.php:242
#4: Bitrix\Main\Entity\DataManager::getList(array)
	/home/bitrix/www/bitrix/modules/main/lib/entity/datamanager.php:171
#5: Bitrix\Main\Entity\DataManager::getRow(array)
	/home/bitrix/www/bitrix/modules/security/classes/general/session_db.php:58
#6: CSecuritySessionDB::read(string)
	
#7: session_start()
	/home/bitrix/www/bitrix/modules/main/include.php:301
#8: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog_before.php:14
#9: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog.php:10
#10: require_once(string)
	/home/bitrix/www/bitrix/header.php:1
#11: require(string)
	/home/bitrix/www/category/index.php:1
#12: include_once(string)
	/home/bitrix/www/bitrix/modules/main/include/urlrewrite.php:159
#13: include_once(string)
	/home/bitrix/www/bitrix/urlrewrite.php:2