I fixed most of the problems I encountered while upgrading from 1.3 to 1.4, the only thing giving me an error now is the “Newsletter Subscribers” Admin section.
Fatal error: Call to a member function getBackend() on a non-object in magento/app/code/core/Mage/Newsletter/Model/Mysql4/Subscriber/Collection.php on line 146
1. Database repair finds no errors
2. Cache has been cleared
3. Happens even if the subscriber list is empty
Any help would be appreciated.