SQLSTATE[08004] [1040] Too many connections

Fatal error:  Uncaught Error: Call to a member function query() on null in /var/www/libs/Rg/Plugins/ScontiPromozioni.php:82
Stack trace:
#0 /var/www/libs/Rg/Carrello/Drivers/CarrelloMysqlDriver.php(26): Rg\Plugins\ScontiPromozioni->scontiInCorso()
#1 /var/www/libs/Rg/Carrello/Carrello.php(18): Rg\Carrello\Drivers\CarrelloMysqlDriver->__construct()
#2 /var/www/libs/Rg/Carrello/Carrello.php(38): Rg\Carrello\Carrello->__construct()
#3 /var/www/libs/Rg/Controllers/AreautenteController.php(72): Rg\Carrello\Carrello::getInstance()
#4 /var/www/libs/Rg/FrontController.php(74): Rg\Controllers\AreautenteController->__construct('signinAction')
#5 /var/www/public/index.php(124): Rg\FrontController->run()
#6 {main}
  thrown in /var/www/libs/Rg/Plugins/ScontiPromozioni.php on line 82