SQLSTATE[08004] [1040] Too many connections

Fatal error:  Uncaught Error: Call to a member function prepare() on null in /var/www/libs/Rg/Plugins/CreaMenuSupercategorie.php:44
Stack trace:
#0 /var/www/libs/Rg/Plugins/CreaMenuSupercategorie.php(32): Rg\Plugins\CreaMenuSupercategorie->menuSupercategorie()
#1 /var/www/libs/Rg/FrontController.php(73): Rg\Plugins\CreaMenuSupercategorie::get()
#2 /var/www/public/index.php(124): Rg\FrontController->run()
#3 {main}
  thrown in /var/www/libs/Rg/Plugins/CreaMenuSupercategorie.php on line 44