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 ( 'date' => 'Thu, Mar 23', 'previousPages' => Piwik\DataTable::__set_state(array( 'rows' => array ( 0 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/c/general-questions', 'referrals' => 2, )), 1 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/users/bssystems/preferences', 'referrals' => 2, )), 2 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/t/piwik-3-administration-page-is-slow-to-open/22723', 'referrals' => 1, )), 3 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/t/welcome-to-piwik-forums/23626', 'referrals' => 1, )), 4 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/t/how-to-include-third-party-library-into-plugin/23624/1', 'referrals' => 1, )), 5 => Piwik\DataTable\Row::__set_state(array( 'label' => 'Others', 'referrals' => 31, )), ), 'currentId' => 1, 'depthLevel' => 0, 'indexNotUpToDate' => true, 'rebuildIndexContinuously' => false, 'tableSortedBy' => false, 'queuedFilters' => array ( ), 'disabledFilters' => array ( ), 'rowsCountBeforeLimitFilter' => 0, 'enableRecursiveSort' => false, 'enableRecursiveFilters' => false, 'rowsIndexByLabel' => array ( ), 'summaryRow' => NULL, 'metadata' => array ( ), 'maximumAllowedRows' => 0, )), 'previousSiteSearches' => Piwik\DataTable::__set_state(array( 'rows' => array ( ), 'currentId' => 2, 'depthLevel' => 0, 'indexNotUpToDate' => true, 'rebuildIndexContinuously' => false, 'tableSortedBy' => false, 'queuedFilters' => array ( ), 'disabledFilters' => array ( ), 'rowsCountBeforeLimitFilter' => 0, 'enableRecursiveSort' => false, 'enableRecursiveFilters' => false, 'rowsIndexByLabel' => array ( ), 'summaryRow' => NULL, 'metadata' => array ( ), 'maximumAllowedRows' => 0, )), 'pageMetrics' => array ( 'loops' => 3, 'pageviews' => 79, 'entries' => 38, 'exits' => 26, ), 'followingPages' => Piwik\DataTable::__set_state(array( 'rows' => array ( 0 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/c/general-questions', 'referrals' => 10, )), 1 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/c/support-bugs', 'referrals' => 8, )), 2 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/c/knowledge-base', 'referrals' => 5, )), 3 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/c/plugins-platform', 'referrals' => 4, )), 4 => Piwik\DataTable\Row::__set_state(array( 'label' => 'forum.piwik.org/c/supporto-in-italiano', 'referrals' => 3, )), 5 => Piwik\DataTable\Row::__set_state(array( 'label' => 'Others', 'referrals' => 13, )), ), 'currentId' => 3, 'depthLevel' => 0, 'indexNotUpToDate' => true, 'rebuildIndexContinuously' => false, 'tableSortedBy' => false, 'queuedFilters' => array ( ), 'disabledFilters' => array ( ), 'rowsCountBeforeLimitFilter' => 0, 'enableRecursiveSort' => false, 'enableRecursiveFilters' => false, 'rowsIndexByLabel' => array ( ), 'summaryRow' => NULL, 'metadata' => array ( ), 'maximumAllowedRows' => 0, )), 'followingSiteSearches' => Piwik\DataTable::__set_state(array( 'rows' => array ( 0 => Piwik\DataTable\Row::__set_state(array( 'label' => 'user id', 'referrals' => 1, )), 1 => Piwik\DataTable\Row::__set_state(array( 'label' => 'Cannot use string offset as an array', 'referrals' => 1, )), 2 => Piwik\DataTable\Row::__set_state(array( 'label' => 'segment', 'referrals' => 1, )), 3 => Piwik\DataTable\Row::__set_state(array( 'label' => 'search keyword', 'referrals' => 1, )), 4 => Piwik\DataTable\Row::__set_state(array( 'label' => 'change user', 'referrals' => 1, )), 5 => Piwik\DataTable\Row::__set_state(array( 'label' => 'Others', 'referrals' => 2, )), ), 'currentId' => 4, 'depthLevel' => 0, 'indexNotUpToDate' => true, 'rebuildIndexContinuously' => false, 'tableSortedBy' => false, 'queuedFilters' => array ( ), 'disabledFilters' => array ( ), 'rowsCountBeforeLimitFilter' => 0, 'enableRecursiveSort' => false, 'enableRecursiveFilters' => false, 'rowsIndexByLabel' => array ( ), 'summaryRow' => NULL, 'metadata' => array ( ), 'maximumAllowedRows' => 0, )), 'outlinks' => Piwik\DataTable::__set_state(array( 'rows' => array ( ), 'currentId' => 5, 'depthLevel' => 0, 'indexNotUpToDate' => true, 'rebuildIndexContinuously' => false, 'tableSortedBy' => false, 'queuedFilters' => array ( ), 'disabledFilters' => array ( ), 'rowsCountBeforeLimitFilter' => 0, 'enableRecursiveSort' => false, 'enableRecursiveFilters' => false, 'rowsIndexByLabel' => array ( ), 'summaryRow' => NULL, 'metadata' => array ( ), 'maximumAllowedRows' => 0, )), 'downloads' => Piwik\DataTable::__set_state(array( 'rows' => array ( ), 'currentId' => 6, 'depthLevel' => 0, 'indexNotUpToDate' => true, 'rebuildIndexContinuously' => false, 'tableSortedBy' => false, 'queuedFilters' => array ( ), 'disabledFilters' => array ( ), 'rowsCountBeforeLimitFilter' => 0, 'enableRecursiveSort' => false, 'enableRecursiveFilters' => false, 'rowsIndexByLabel' => array ( ), 'summaryRow' => NULL, 'metadata' => array ( ), 'maximumAllowedRows' => 0, )), 'referrers' => array ( 0 => array ( 'label' => 'Direct Entries', 'shortName' => 'direct', 'visits' => 17, 'details' => array ( ), ), 1 => array ( 'label' => 'From Search Engines', 'shortName' => 'search', 'visits' => 4, 'details' => array ( ), ), 2 => array ( 'label' => 'From Websites', 'shortName' => 'website', 'visits' => 17, 'details' => array ( 0 => array ( 'label' => 'https://piwik.org/', 'referrals' => '3', ), 1 => array ( 'label' => 'http://210.222.27.5/tm/?a=CR&b=MAC&c=3228552&d=31&e=32&f=Zm9ydW0ucGl3aWsub3Jn&g=1490233573079&h=1490233573192&y=10&z=0&x=2&w=2017-03-24&in=032_00044321&id=20170323', 'referrals' => '1', ), 2 => array ( 'label' => 'https://piwik.org/docs/user-id/', 'referrals' => '1', ), 3 => array ( 'label' => 'https://piwik.org/get-involved/', 'referrals' => '1', ), 4 => array ( 'label' => 'https://piwik.org/docs/users-flow/', 'referrals' => '1', ), 5 => array ( 'label' => 'Others', 'referrals' => '10', ), ), ), ), );