Error: Data structure returned is not convertible in the requested format: Only integer keys supported for array columns on base level. Unsupported string 'pageMetrics' found for row 'array (
  'loops' => 13,
  'pageviews' => 224,
  'entries' => 167,
  'exits' => 115,
)'. Try to call this method with the parameters '&format=original&serialize=1'; you will get the original php data structure serialized.