Duplicate XF2 Upgrade Member List Error

Affected version
2.0 beta 3


Successfully upgrade from 1.5.14 to 2.0 beta 3 upgraded. Everything is smooth.

But, members list (index.php?members/) does not open and gives the following error.

InvalidArgumentException: Attempted to convert object to JSON array (cache_results) in src/XF/Mvc/Entity/Entity.php at line 766
XF\Mvc\Entity\Entity->_castValueToType() in src/XF/Mvc/Entity/Entity.php at line 617
XF\Mvc\Entity\Entity->set() in src/XF/Mvc/Entity/Entity.php at line 547
XF\Mvc\Entity\Entity->__set() in src/XF/Service/MemberStat/Preparer.php at line 65
XF\Service\MemberStat\Preparer->cache() in src/XF/Service/MemberStat/Preparer.php at line 88
XF\Service\MemberStat\Preparer->getResults() in src/XF/Entity/MemberStat.php at line 68
XF\Entity\MemberStat->getResults() in src/XF/Pub/Controller/Member.php at line 110
XF\Pub\Controller\Member->actionIndex() in src/XF/Mvc/Dispatcher.php at line 249
XF\Mvc\Dispatcher->dispatchClass() in src/XF/Mvc/Dispatcher.php at line 89
XF\Mvc\Dispatcher->dispatchLoop() in src/XF/Mvc/Dispatcher.php at line 41
XF\Mvc\Dispatcher->run() in src/XF/App.php at line 1787
XF\App->run() in src/XF.php at line 326
XF::runApp() in index.php at line 13