Magento Error: Fatal error: Call to a member function rewrite() on a non-object in app/code/core/Mage/Core/Controller/Varien/Front.php on line 165

Magento Error: Fatal error: Call to a member function rewrite() on a non-object in /var/www/magento/app/code/core/Mage/Core/Controller/Varien/Front.php on line 165

While upgrading Magento from 1.7 to 1.8 version, this error generally appears and stops the site from loading.

We can get rid of this error simply by clearing the cache:

rm -rf var/cache/*

If you don’t have terminal access, clear all the contents of var/cache/ directory.

Further if you have memcached or other caching system installed, flush them as well.