One of the most important tasks you need to remember after each major change (and before Magento upgrade) is to clean up your Magento cache.
Login to Admin Panel
Go to System Cache Management
Select all Cache Types, choose Refresh from the Action dropdown and click on Submit button
Click on Flush Magento Cache
Click on Flush Cache Storage
Click on Flush Catalog Images Cache
Not satisfied? Then login to your Linux server and clean up tha cache folder manually
SSH to your server
Go to Magento folder (e.g. cd /path/to/magento/folder)
Go to cache folder (var/cache )
Delete all folders (# rm -rf mage–*) (cache folder names start with “mage–”)
Still think the cache is not clean?