[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` = 'uYsyLtBnqlSRjONeWDwZN1WGwae620PX'
LIMIT 0, 1

/home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php:138
#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:1757
#2: Bitrix\Main\Entity\Query->query(string)
	/home/bitrix/www/bitrix/modules/main/lib/entity/query.php:454
#3: Bitrix\Main\Entity\Query->exec()
	/home/bitrix/www/bitrix/modules/main/lib/entity/datamanager.php:230
#4: Bitrix\Main\Entity\DataManager::getList(array)
	/home/bitrix/www/bitrix/modules/main/lib/entity/datamanager.php:159
#5: Bitrix\Main\Entity\DataManager::getRow(array)
	/home/bitrix/www/bitrix/modules/security/classes/general/session_db.php:59
#6: CSecuritySessionDB::read(string)
	
#7: session_start()
	/home/bitrix/www/bitrix/modules/main/include.php:285
#8: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog_before.php:16
#9: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog.php:11
#10: require_once(string)
	/home/bitrix/www/bitrix/header.php:1
#11: require(string)
	/home/bitrix/www/news/index.php:2

Fatal error: Uncaught exception 'Bitrix\Main\DB\SqlQueryException' with message 'Mysql query error: (2006) MySQL server has gone away' in /home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php:138 Stack trace: #0 /home/bitrix/www/bitrix/modules/main/lib/db/mysqlcommonconnection.php(132): Bitrix\Main\DB\MysqliConnection->queryInternal('SELECT * FROM `...') #1 /home/bitrix/www/bitrix/modules/main/lib/db/connection.php(715): Bitrix\Main\DB\MysqlCommonConnection->getTableFields('b_sec_session') #2 /home/bitrix/www/bitrix/modules/main/lib/db/sqlhelper.php(362): Bitrix\Main\DB\Connection->getTableField('b_sec_session', 'SESSION_ID') #3 /home/bitrix/www/bitrix/modules/main/lib/entity/datamanager.php(799): Bitrix\Main\DB\SqlHelper->prepareAssignment('b_sec_session', 'SESSION_ID', 'uYsyLtBnqlSRjON...') #4 /home/bitrix/www/bitrix/modules/security/classes/general/session_db.php(87): Bitrix\Main\Entity\DataManager::delete('uYsyLtBnqlSRjON...') #5 [internal function]: CSecuritySessionDB::write('uYsyLtBnqlSRjON...', '') #6 [i in /home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php on line 138