ERROR: delete on table violates foreign key constraint. Key id is still referenced from table (many)
From Rails v4.2 you can do this: Create a migration to update the foreign keys 20160321165946_update_foreign_key.rb class UpdateForeignKey < ActiveRecord::Migration def change # remove the old foreign_key remove_foreign_key :posts, :users # add the new foreign_key add_foreign_key :posts, :users, on_delete: :cascade end end