Unable to open PDO connection [wrapped: SQLSTATE[HY000] [1040] Too many connections]

#0 /var/www/html/ula/common/propel/runtime/lib/Propel.php(574): Propel::initConnection(Array, 'zyndio')
#1 /var/www/html/ula/common/propel/runtime/lib/Propel.php(600): Propel::getMasterConnection('zyndio')
#2 /var/www/html/ula/common/propel/runtime/lib/Propel.php(550): Propel::getSlaveConnection('zyndio')
#3 /var/www/html/ula/common/propel/runtime/lib/query/ModelCriteria.php(1217): Propel::getConnection('zyndio', 'read')
#4 /var/www/html/ula/common/propel/runtime/lib/query/ModelCriteria.php(1105): ModelCriteria->getSelectStatement(NULL)
#5 /var/www/html/ula/models/searchcategoryparentdata.class.php(80): ModelCriteria->find()
#6 /var/www/html/ula/models/searchcategorydata.class.php(142): SearchCategoryParentData->getCategoryList(1)
#7 /var/www/html/ula/controllers/pages/yunkpagecontroller.class.php(222): SearchCategoryData->getCategoriesByParent(1, '')
#8 /var/www/html/ula/controllers/core/core.class.php(386): YunkPageController->run()
#9 /var/www/html/ula/controllers/core/core.class.php(569): Yunk::pageController()
#10 /var/www/html/ula/html/zyndio.php(7): Yunk::run('page')
#11 {main}