Unable to find writable var_dir

#0 /var/www/sites/www.scoutvaror.se/app/code/core/Mage/Core/Model/Config/Options.php(66): Mage_Core_Model_Config_Options->getVarDir()
#1 /var/www/sites/www.scoutvaror.se/lib/Varien/Object.php(112): Mage_Core_Model_Config_Options->_construct()
#2 /var/www/sites/www.scoutvaror.se/app/code/core/Mage/Core/Model/Config.php(200): Varien_Object->__construct(Array)
#3 /var/www/sites/www.scoutvaror.se/app/Mage.php(635): Mage_Core_Model_Config->__construct(Array)
#4 /var/www/sites/www.scoutvaror.se/index.php(92): Mage::run('', 'store')
#5 {main}