[Bitrix\Main\DB\ConnectionException] 
Mysql connect error [localhost]: (2002) Connection refused (400)
/var/www/clients/client0/web1/web/bitrix/modules/main/lib/db/mysqliconnection.php:65
#0: Bitrix\Main\DB\MysqliConnection->connectInternal
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/db/mysqliconnection.php:122
#1: Bitrix\Main\DB\MysqliConnection->queryInternal
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/db/connection.php:330
#2: Bitrix\Main\DB\Connection->query
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/modulemanager.php:20
#3: Bitrix\Main\ModuleManager::getInstalledModules
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/loader.php:77
#4: Bitrix\Main\Loader::includeModule
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/data/connectionpool.php:308
#5: Bitrix\Main\Data\ConnectionPool->createSlaveConnection
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/data/connectionpool.php:247
#6: Bitrix\Main\Data\ConnectionPool->getSlaveConnection
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/db/connection.php:318
#7: Bitrix\Main\DB\Connection->query
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/eventmanager.php:242
#8: Bitrix\Main\EventManager->loadEventHandlers
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/eventmanager.php:340
#9: Bitrix\Main\EventManager->findEventHandlers
	/var/www/clients/client0/web1/web/bitrix/modules/main/classes/general/module.php:340
#10: GetModuleEvents
	/var/www/clients/client0/web1/web/bitrix/modules/main/include.php:280
#11: require_once(string)
	/var/www/clients/client0/web1/web/bitrix/modules/main/include/prolog_before.php:14
#12: require_once(string)
	/var/www/clients/client0/web1/web/bitrix/modules/main/include/prolog.php:10
#13: require_once(string)
	/var/www/clients/client0/web1/web/bitrix/header.php:1
#14: require(string)
	/var/www/clients/client0/web1/private/amp/404.php:5
#15: include_once(string)
	/var/www/clients/client0/web1/web/bitrix/urlrewrite.php:4