Fatal error: Uncaught League\Flysystem\Exception: Impossible to create the root directory "/var/www/files". mkdir(): Permission denied in /var/www/html/lib/pkp/lib/vendor/league/flysystem/src/Adapter/Local.php:112 Stack trace: #0 /var/www/html/lib/pkp/lib/vendor/league/flysystem/src/Adapter/Local.php(78): League\Flysystem\Adapter\Local->ensureDirectory() #1 /var/www/html/lib/pkp/classes/services/PKPFileService.inc.php(46): League\Flysystem\Adapter\Local->__construct() #2 /var/www/html/classes/services/OJSServiceProvider.inc.php(51): PKP\Services\PKPFileService->__construct() #3 /var/www/html/lib/pkp/lib/vendor/pimple/pimple/src/Pimple/Container.php(118): APP\Services\OJSServiceProvider->APP\Services\{closure}() #4 /var/www/html/lib/pkp/classes/core/PKPServices.inc.php(69): Pimple\Container->offsetGet() #5 /var/www/html/lib/pkp/classes/core/PKPServices.inc.php(50): PKPServices->_getFromContainer() #6 /var/www/html/pages/article/ArticleHandler.inc.php(429): PKPServices::get() #7 /var/www/html/lib/pkp/classes/core/PKPRouter.inc.php(395): ArticleHandler->download() #8 /var/www/html/lib/pkp/classes/core/PKPPageRouter.inc.php(246): PKPRouter->_authorizeInitializeAndCallRequest() #9 /var/www/html/lib/pkp/classes/core/Dispatcher.inc.php(144): PKPPageRouter->route() #10 /var/www/html/lib/pkp/classes/core/PKPApplication.inc.php(362): Dispatcher->dispatch() #11 /var/www/html/index.php(69): PKPApplication->execute() #12 {main} thrown in /var/www/html/lib/pkp/lib/vendor/league/flysystem/src/Adapter/Local.php on line 112