Error:  Data structure returned is not convertible in the requested format. Try to call this method with the parameters '&format=original&serialize=1'; you will get the original php data structure serialized. The data structure looks like this: 
 $data = array (
  0 => 
  array (
    'name' => 'Dashboard',
    'id' => 1,
    'widgets' => 
    array (
      0 => 
      array (
        'module' => 'Live',
        'action' => 'widget',
      ),
      1 => 
      array (
        'module' => 'VisitsSummary',
        'action' => 'getEvolutionGraph',
      ),
      2 => 
      array (
        'module' => 'Referrers',
        'action' => 'getReferrerType',
      ),
      3 => 
      array (
        'module' => 'VisitsSummary',
        'action' => 'get',
      ),
    ),
  ),
);