Fatal error: Uncaught exception 'Mage_Core_Exception' with message 'Unable to find writable var_dir' in /var/www/prod/app/code/core/Mage/Core/Model/Config/Options.php:152
Stack trace:
#0 /var/www/prod/app/code/core/Mage/Core/Model/Config/Options.php(66): Mage_Core_Model_Config_Options->getVarDir()
#1 /var/www/prod/lib/Varien/Object.php(112): Mage_Core_Model_Config_Options->_construct()
#2 /var/www/prod/app/code/core/Mage/Core/Model/Config.php(200): Varien_Object->__construct(NULL)
#3 /var/www/prod/app/code/local/NBSSystem/Nitrogento/Helper/Data.php(100): Mage_Core_Model_Config->__construct()
#4 /var/www/prod/app/code/local/NBSSystem/Nitrogento/Main.php(27): NBSSystem_Nitrogento_Helper_Data::getSimpleConfig()
#5 /var/www/prod/app/code/local/NBSSystem/Nitrogento/Main.php(17): NBSSystem_Nitrogento_Main::getInstanceName('NBSSystem_Nitro...')
#6 /var/www/prod/app/code/local/NBSSystem/Nitrogento/Main.php(53): NBSSystem_Nitrogento_Main::getInstance()
#7 /var/www/prod/index.php(91): NBSSystem_Nitrogento_Main::init()
#8 {main}
t in /var/www/prod/app/code/core/Mage/Core/Model/Config/Options.php on line 152