[Bitrix\Main\DB\ConnectionException] 
Mysql connect error [localhost]: (2006) MySQL server has gone away (400)
/home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php:85
#0: Bitrix\Main\DB\MysqliConnection->connectInternal
	/home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php:137
#1: Bitrix\Main\DB\MysqliConnection->queryInternal
	/home/bitrix/www/bitrix/modules/main/lib/db/connection.php:327
#2: Bitrix\Main\DB\Connection->query
	/home/bitrix/www/bitrix/modules/main/lib/db/mysqlcommonconnection.php:290
#3: Bitrix\Main\DB\MysqlCommonConnection->lock
	/home/bitrix/www/bitrix/modules/main/lib/composite/internals/locker.php:24
#4: Bitrix\Main\Composite\Internals\Locker::lock
	/home/bitrix/www/bitrix/modules/main/lib/composite/engine.php:478
#5: Bitrix\Main\Composite\Engine::processPageContent
	/home/bitrix/www/bitrix/modules/main/lib/composite/engine.php:425
#6: Bitrix\Main\Composite\Engine::endBuffering
	/home/bitrix/www/bitrix/modules/main/classes/general/main.php:3206
#7: CAllMain->EndBufferContent
	/home/bitrix/www/bitrix/modules/main/classes/general/main.php:3149
#8: CAllMain->EndBufferContentMan
	/home/bitrix/www/bitrix/modules/main/include/epilog_after.php:46
#9: require(string)
	/home/bitrix/www/bitrix/modules/main/include/epilog.php:3
#10: require_once(string)
	/home/bitrix/www/bitrix/footer.php:4
#11: require(string)
	/home/bitrix/www/catalog/index.php:2369
#12: include_once(string)
	/home/bitrix/www/bitrix/modules/main/include/urlrewrite.php:184
#13: include_once(string)
	/home/bitrix/www/bitrix/urlrewrite.php:2
----------

Fatal error: Uncaught Bitrix\Main\DB\SqlQueryException: Mysql query error: (2006) MySQL server has gone away in /home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php:149 Stack trace: #0 /home/bitrix/www/bitrix/modules/main/lib/db/mysqlcommonconnection.php(93): Bitrix\Main\DB\MysqliConnection->queryInternal() #1 /home/bitrix/www/bitrix/modules/main/lib/db/connection.php(815): Bitrix\Main\DB\MysqlCommonConnection->getTableFields() #2 /home/bitrix/www/bitrix/modules/main/lib/db/sqlhelper.php(423): Bitrix\Main\DB\Connection->getTableField() #3 /home/bitrix/www/bitrix/modules/main/lib/orm/data/datamanager.php(1669): Bitrix\Main\DB\SqlHelper->prepareAssignment() #4 /home/bitrix/www/bitrix/modules/main/lib/session/handlers/databasesessionhandler.php(60): Bitrix\Main\ORM\Data\DataManager::delete() #5 /home/bitrix/www/bitrix/modules/main/lib/session/handlers/databasesessionhandler.php(38): Bitrix\Main\Session\Handlers\DatabaseSessionHandler->processDestroy() #6 /home/bitrix/www/bitrix/modules/main/lib/session/handlers/abstractsessionhandler.php(88): Bitrix\Main\Session\Handlers\DatabaseSessionHandler->processWrite() #7 [internal function]: Bitrix\Main\Session\Handlers\AbstractSessionHandler->write() #8 [internal function]: session_write_close() #9 {main} thrown in /home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php on line 149