[Bitrix\Main\DB\SqlQueryException] 
Mysql query error: (2006) MySQL server has gone away (400)

					SELECT
						`CONDITION`,
						TEMPLATE,
						SITE_ID
					FROM
						b_site_template
					ORDER BY
						SITE_ID,
						CASE
							WHEN IFNULL(LENGTH(`CONDITION`), 0)=0 THEN 2
							ELSE 1
						END,
						SORT
				
/var/www/clients/client0/web1/web/bitrix/modules/main/lib/db/mysqliconnection.php:137
#0: Bitrix\Main\DB\MysqliConnection->queryInternal
	/var/www/clients/client0/web1/web/bitrix/modules/main/lib/db/connection.php:330
#1: Bitrix\Main\DB\Connection->query
	/var/www/clients/client0/web1/web/bitrix/modules/main/classes/general/main.php:4568
#2: CAllSite::GetCurTemplate
	/var/www/clients/client0/web1/web/bitrix/modules/main/include.php:522
#3: require_once(string)
	/var/www/clients/client0/web1/web/bitrix/modules/main/include/prolog_before.php:14
#4: require_once(string)
	/var/www/clients/client0/web1/web/bitrix/modules/main/include/prolog.php:10
#5: require_once(string)
	/var/www/clients/client0/web1/web/bitrix/header.php:1
#6: require(string)
	/var/www/clients/client0/web1/web/404.php:5
#7: include_once(string)
	/var/www/clients/client0/web1/web/bitrix/urlrewrite.php:4