 <p>Have you created all the necessary columns for your associations? Your schema for your taggings table should look similar to this</p> <pre><code>create_table "taggings", force: :cascade do |t| t.integer "token_id", limit: 4 t.integer "taggable_id", limit: 4 t.string "taggable_type", limit: 255 t.datetime "created_at", null: false t.datetime "updated_at", null: false end </code></pre> <p>I think you are missing the <code>token_id</code> column or forgot to perform a migration.</p>