JSON RPC error at method package.producer.getProducerFromRewriteTitle

#0  JsonRpcClient->exec(package.producer.getProducerFromRewriteTitle, podprsenka-change-exclusive-smetanova) called at [/var/www/prod/rozbaleno/shared/inc/Eshop/UrlResolving/UrlResolver.php:500]
#1  Eshop\UrlResolving\UrlResolver->getProducerByRewriteTitle(podprsenka-change-exclusive-smetanova) called at [/var/www/prod/rozbaleno/shared/inc/Eshop/UrlResolving/UrlResolver.php:369]
#2  Eshop\UrlResolving\UrlResolver->getCategoryOrProductListPair(damske-spodni-pradlo, podprsenka-change-exclusive-smetanova) called at [/var/www/prod/rozbaleno/shared/inc/Eshop/UrlResolving/UrlResolver.php:189]
#3  Eshop\UrlResolving\UrlResolver->generatePair(damske-spodni-pradlo, podprsenka-change-exclusive-smetanova) called at [/var/www/prod/rozbaleno/shared/inc/Eshop/UrlResolving/UrlResolver.php:88]
#4  Eshop\UrlResolving\UrlResolver->getControllerActionPair(damske-spodni-pradlo, podprsenka-change-exclusive-smetanova) called at [/var/www/prod/rozbaleno/eshop/index.php:24]

Server JSON response:

Unable to connect to DB: mysqli_connect(): (HY000/2002): Connection refused
#0 [internal function]: exceptionErrorHandler(2, 'mysqli_connect(...', '/var/www/prod/r...', 78, Array)
#1 /var/www/prod/rozbaleno/shared/libs/db/db.mysql.class.php(78): mysqli_connect('prod-rzb-db-01....', 'rzb', 'xuo3uoSh', 'auctionmaster')
#2 /var/www/prod/rozbaleno/shared/libs/db/db.generic.class.php(141): MySQLDb->_connect()
#3 /var/www/prod/rozbaleno/shared/libs/db/db.mysql.class.php(25): GenericDb->connect('prod-rzb-db-01....', 'rzb', 'xuo3uoSh', 'auctionmaster')
#4 /var/www/prod/rozbaleno/shared/libs/db/db.mysql.class.php(43): MySQLDb->__construct()
#5 /var/www/prod/rozbaleno/api/classes/packageproducerfactory.class.php(302): MySQLDb::init()
#6 /var/www/prod/rozbaleno/api/libs/JsonRpcServer.class.php(247): PackageProducerFactory::getProducerFromRewriteTitle('podprsenka-chan...')
#7 /var/www/prod/rozbaleno/api/libs/JsonRpcServer.class.php(182): JsonRpcServer->call('package.produce...', Array)
#8 /var/www/prod/rozbaleno/api/server.php(8): JsonRpcServer->process()
#9 {main}