I am beginner in pimcore cms. When I open setting>objects>classes
I couldn't see the list of classes in classes window. I checked error log and found the following error:
PHP Fatal error: Uncaught Error: Call to a member function getId() on null in /var/www/html/pimcore/pimcore/modules/admin/controllers/ClassController.php:75
Stack trace:
#0 /var/www/html/pimcore/vendor/zendframework/zendframework1/library/Zend/Controller/Action.php(516): Admin_ClassController->getTreeAction()
#1 /var/www/html/pimcore/vendor/zendframework/zendframework1/library/Zend/Controller/Dispatcher/Standard.php(308): Zend_Controller_Action->dispatch('getTreeAction')
#2 /var/www/html/pimcore/vendor/zendframework/zendframework1/library/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#3 /var/www/html/pimcore/pimcore/lib/Pimcore.php(159): Zend_Controller_Front->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#4 /var/www/html/pimcore/pimcore/lib/Pimcore.php(125): Pimcore::runDispatcher(Object(Zend_Controller_Front), false, NULL, NULL)
#5 /var/www/html/pimcore/index.php(23): Pimcore:: in /var/www/html/pimcore/pimcore/modules/admin/controllers/ClassController.php on line 75
I couldn't find out what went wrong, also I'm absolute beginner in pimcore.