Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 1041 Out of memory; check if mysqld or some other process uses all available memory; if not, you may have to use 'ulimit' to allow mysqld to use more memory or you can add more swap space in /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php:412 Stack trace: #0 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(412): PDOStatement->execute() #1 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(812): Illuminate\Database\Connection->Illuminate\Database\{closure}() #2 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(779): Illuminate\Database\Connection->runQueryCallback() #3 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(398): Illuminate\Database\Connection->run() #4 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3106): Illuminate\Database\Connection->select() #5 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3091): Illuminate\Database\Query\Builder->runSelect() #6 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3676): Illuminate\Database\Query\Builder->Illuminate\Database\Query\{closure}() #7 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3090): Illuminate\Database\Query\Builder->onceWithColumns() #8 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/category/DAO.php(98): Illuminate\Database\Query\Builder->get() #9 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/category/Collector.php(63): PKP\category\DAO->getMany() #10 /var/www/vst/ojs-3.5.0-1/pages/article/ArticleHandler.php(254): PKP\category\Collector->getMany() #11 [internal function]: APP\pages\article\ArticleHandler->view() #12 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/core/PKPRouter.php(327): call_user_func() #13 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/core/PKPPageRouter.php(249): PKP\core\PKPRouter->_authorizeInitializeAndCallRequest() #14 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/core/Dispatcher.php(157): PKP\core\PKPPageRouter->route() #15 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/core/PKPApplication.php(426): PKP\core\Dispatcher->dispatch() #16 /var/www/vst/ojs-3.5.0-1/00.php(21): PKP\core\PKPApplication->execute() #17 /var/www/vst/ojs-3.5.0-1/index.php(14): include('...') #18 {main} Next Illuminate\Database\QueryException: SQLSTATE[HY000]: General error: 1041 Out of memory; check if mysqld or some other process uses all available memory; if not, you may have to use 'ulimit' to allow mysqld to use more memory or you can add more swap space (Connection: mysql, SQL: select `c`.* from `categories` as `c` left join `categories` as `pc` on `c`.`parent_id` = `pc`.`category_id` where `c`.`category_id` in (select `category_id` from `publication_categories` where `publication_id` in (11761)) order by (COALESCE((pc.seq * 8192) + pc.category_id, 0) * 8192) + CASE WHEN pc.category_id IS NULL THEN 8192 * ((c.seq * 8192) + c.category_id) ELSE c.seq END asc) in /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php:825 Stack trace: #0 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(779): Illuminate\Database\Connection->runQueryCallback() #1 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(398): Illuminate\Database\Connection->run() #2 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3106): Illuminate\Database\Connection->select() #3 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3091): Illuminate\Database\Query\Builder->runSelect() #4 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3676): Illuminate\Database\Query\Builder->Illuminate\Database\Query\{closure}() #5 /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3090): Illuminate\Database\Query\Builder->onceWithColumns() #6 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/category/DAO.php(98): Illuminate\Database\Query\Builder->get() #7 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/category/Collector.php(63): PKP\category\DAO->getMany() #8 /var/www/vst/ojs-3.5.0-1/pages/article/ArticleHandler.php(254): PKP\category\Collector->getMany() #9 [internal function]: APP\pages\article\ArticleHandler->view() #10 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/core/PKPRouter.php(327): call_user_func() #11 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/core/PKPPageRouter.php(249): PKP\core\PKPRouter->_authorizeInitializeAndCallRequest() #12 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/core/Dispatcher.php(157): PKP\core\PKPPageRouter->route() #13 /var/www/vst/ojs-3.5.0-1/lib/pkp/classes/core/PKPApplication.php(426): PKP\core\Dispatcher->dispatch() #14 /var/www/vst/ojs-3.5.0-1/00.php(21): PKP\core\PKPApplication->execute() #15 /var/www/vst/ojs-3.5.0-1/index.php(14): include('...') #16 {main} thrown in /var/www/vst/ojs-3.5.0-1/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php on line 825