[Bitrix\Main\DB\ConnectionException] 
Mysql connect error [localhost]: (2002) Connection refused (400)
/home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php:65
#0: Bitrix\Main\DB\MysqliConnection->connectInternal
	/home/bitrix/www/bitrix/modules/main/lib/db/mysqliconnection.php:122
#1: Bitrix\Main\DB\MysqliConnection->queryInternal
	/home/bitrix/www/bitrix/modules/main/lib/db/connection.php:330
#2: Bitrix\Main\DB\Connection->query
	/home/bitrix/www/bitrix/modules/main/lib/orm/query/query.php:3357
#3: Bitrix\Main\ORM\Query\Query->query
	/home/bitrix/www/bitrix/modules/main/lib/orm/query/query.php:825
#4: Bitrix\Main\ORM\Query\Query->exec
	/home/bitrix/www/bitrix/modules/main/lib/orm/data/datamanager.php:500
#5: Bitrix\Main\ORM\Data\DataManager::getList
	/home/bitrix/www/bitrix/modules/abtest/lib/helper.php:39
#6: Bitrix\ABTest\Helper::getActiveTest
	/home/bitrix/www/bitrix/modules/abtest/lib/helper.php:126
#7: Bitrix\ABTest\Helper::getContext
	/home/bitrix/www/bitrix/modules/abtest/lib/eventhandler.php:37
#8: Bitrix\ABTest\EventHandler::onGetCurrentSiteTemplate
	
#9: call_user_func_array
	/home/bitrix/www/bitrix/modules/main/lib/eventmanager.php:435
#10: Bitrix\Main\EventManager->sendToEventHandler
	/home/bitrix/www/bitrix/modules/main/lib/eventmanager.php:371
#11: Bitrix\Main\EventManager->send
	/home/bitrix/www/bitrix/modules/main/lib/event.php:142
#12: Bitrix\Main\Event->send
	/home/bitrix/www/bitrix/modules/main/classes/general/main.php:4585
#13: CAllSite::GetCurTemplate
	/home/bitrix/www/bitrix/modules/main/include.php:534
#14: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog_before.php:14
#15: require_once(string)
	/home/bitrix/www/bitrix/modules/main/include/prolog.php:10
#16: require_once(string)
	/home/bitrix/www/bitrix/header.php:1
#17: require(string)
	/home/bitrix/www/part/index.php:2
#18: include_once(string)
	/home/bitrix/www/bitrix/modules/main/include/urlrewrite.php:159
#19: include_once(string)
	/home/bitrix/www/bitrix/urlrewrite.php:2