I’ve just been dealing with a task to upgrade a Magento 126.96.36.199 site to Magento 188.8.131.52. I was supplied the site files and a database dump. All this installed fine and the updater ran without a hitch. However, upon return to the Magento admin, I received the dreaded “There has been an error processing your request” page. Looking at the error report, I saw:
Base table or view already exists: 1050 Table ‘sales_flat_order’ already exists
After some investigating, it transpired that an upgrade had been previously attempted but failed, so the roll back replaced the files and re-loaded the original, pre-upgrade database but of course any new tables created by the upgrade scripts have remained as the import only dropped and re-created the ones in the sql script.
The lesson here is to drop the database completely, create it again and then re-import the backup to restore the exact original state.
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