Mage registry key “_singleton/core/resource” already exists

Ever had the “Mage registry key “_singleton/core/resource” already exists” error in Magento and can’t get rid of it? First of all, if you search this on Google, don’t believe anything you read in the first 2-3 pages of results (pages > 3 don’t matter anyway, that’s a black hole…). Even found a champ claiming to “solve” the issue by clearing the cache in index.php EVERY TIME a page was loaded… What’s the point in having a cache engine then? Especially if you’re using the EE version!

Anyway, check if you have APC installed on the box and tweak the


in the apc.ini file.

Hope this helps anyone.