ocs2 has produced an error
  Message: WARNING: mkdir(): No space left on device
  In file: /srv/www/conferences.vntu.edu.ua/html/lib/pkp/lib/adodb/adodb.inc.php
  At line: 1632
  Stacktrace: 
   File: (unknown) line (unknown)
     Function: PKPApplication->errorHandler(2, "mkdir(): No space left on device", "/srv/www/conferences.vntu.edu.ua/html/lib/pkp/lib/adodb/adodb.in...", 1632, Array(9))
   File: /srv/www/conferences.vntu.edu.ua/html/lib/pkp/lib/adodb/adodb.inc.php line 1632
     Function: mkdir("/srv/www/conferences.vntu.edu.ua/html/cache/_db/25", 505)
   File: /srv/www/conferences.vntu.edu.ua/html/lib/pkp/lib/adodb/adodb.inc.php line 1668
     Function: ADOConnection->_gencachename("SELECT	p.paper_id,
				COALESCE(ptl.setting_value, ptpl.setting_...", True)
   File: /srv/www/conferences.vntu.edu.ua/html/lib/pkp/classes/db/DAO.inc.php line 107
     Function: ADOConnection->CacheExecute(3600, "SELECT	p.paper_id,
				COALESCE(ptl.setting_value, ptpl.setting_...", Array(6))
   File: /srv/www/conferences.vntu.edu.ua/html/classes/paper/PublishedPaperDAO.inc.php line 486
     Function: DAO->retrieveCached("SELECT	p.paper_id,
				COALESCE(ptl.setting_value, ptpl.setting_...", Array(6))
   File: /srv/www/conferences.vntu.edu.ua/html/pages/search/SearchHandler.inc.php line 189
     Function: PublishedPaperDAO->getPublishedPaperIdsAlphabetizedByTitle("40", "146", Object(DBResultRange))
   File: /srv/www/conferences.vntu.edu.ua/html/lib/pkp/classes/core/PKPPageRouter.inc.php line 177
     Function: SearchHandler->titles(Array(0), Object(Request))
   File: /srv/www/conferences.vntu.edu.ua/html/lib/pkp/classes/core/Dispatcher.inc.php line 130
     Function: PKPPageRouter->route(Object(Request))
   File: /srv/www/conferences.vntu.edu.ua/html/lib/pkp/classes/core/PKPApplication.inc.php line 170
     Function: Dispatcher->dispatch(Object(Request))
   File: /srv/www/conferences.vntu.edu.ua/html/index.php line 65
     Function: PKPApplication->execute()
  Server info:
   OS: Linux
   PHP Version: 5.6.40-65+ubuntu18.04.1+deb.sury.org+1
   Apache Version: Apache/2.4.29 (Ubuntu)
   DB Driver: mysql
   DB server version: 5.7.42-0ubuntu0.18.04.1<br/>