Error:  Data structure returned is not convertible in the requested format. Try to call this method with the parameters '&amp;format=original&amp;serialize=1'; you will get the original php data structure serialized. The data structure looks like this: 
 $data = array (
  0 =&gt; 
  array (
    'id' =&gt; 'tagmanager_write',
    'name' =&gt; 'Write',
    'description' =&gt; 'Grants the ability to use the Tag Manager. For example create, delete, and manage containers, tags, triggers, and variables, versions, etc.',
    'helpUrl' =&gt; '',
    'includedInRoles' =&gt; 
    array (
      0 =&gt; 'write',
      1 =&gt; 'admin',
    ),
    'category' =&gt; 'Tag Manager',
  ),
  1 =&gt; 
  array (
    'id' =&gt; 'tagmanager_publish_live_container',
    'name' =&gt; 'Publish Live Container',
    'description' =&gt; 'Grants the ability to publish a container to the live environment.',
    'helpUrl' =&gt; '',
    'includedInRoles' =&gt; 
    array (
      0 =&gt; 'admin',
    ),
    'category' =&gt; 'Tag Manager',
  ),
  2 =&gt; 
  array (
    'id' =&gt; 'tagmanager_use_custom_templates',
    'name' =&gt; 'Use Custom Templates',
    'description' =&gt; 'Grants the ability to write HTML/JavaScript that will be executed on the website. Grant this capability only to users you trust as custom templates can be misused to steal for example sensitive information.',
    'helpUrl' =&gt; '',
    'includedInRoles' =&gt; 
    array (
      0 =&gt; 'admin',
    ),
    'category' =&gt; 'Tag Manager',
  ),
);