Unable to find writable var_dir

#0 /var/www/vhosts/annabella.it/httpdocs/app/code/core/Mage/Core/Model/Config/Options.php(66): Mage_Core_Model_Config_Options->getVarDir()
#1 /var/www/vhosts/annabella.it/httpdocs/lib/Varien/Object.php(112): Mage_Core_Model_Config_Options->_construct()
#2 /var/www/vhosts/annabella.it/httpdocs/app/code/core/Mage/Core/Model/Config.php(200): Varien_Object->__construct(Array)
#3 /var/www/vhosts/annabella.it/httpdocs/app/Mage.php(739): Mage_Core_Model_Config->__construct(Array)
#4 /var/www/vhosts/annabella.it/httpdocs/app/Mage.php(678): Mage::_setConfigModel(Array)
#5 /var/www/vhosts/annabella.it/httpdocs/index.php(125): Mage::run('it', 'store')
#6 {main}