Error: Data structure returned is not convertible in the requested format: Only integer keys supported for array columns on base level. Unsupported string 'totals' found for row 'array ( 'nb_pageviews' => '25,540', 'nb_visits' => '10,490', 'hits' => '31,009', 'nb_actions' => '30,391', 'revenue' => '73,853', 'previous_nb_pageviews' => '27,882', 'previous_nb_visits' => '10,958', 'previous_hits' => '33,396', 'previous_nb_actions' => '32,791', 'previous_revenue' => '95,197.05', )'. Try to call this method with the parameters '&format=original&serialize=1'; you will get the original php data structure serialized.