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' =&gt; '28,184',
  'nb_visits' =&gt; '11,039',
  'hits' =&gt; '33,764',
  'nb_actions' =&gt; '33,139',
  'revenue' =&gt; '95,953.95',
  'previous_nb_pageviews' =&gt; '24,463',
  'previous_nb_visits' =&gt; '9,122',
  'previous_hits' =&gt; '29,754',
  'previous_nb_actions' =&gt; '29,257',
  'previous_revenue' =&gt; '90,199.50',
)'. Try to call this method with the parameters '&amp;format=original&amp;serialize=1'; you will get the original php data structure serialized.