CMSurfException(1064) "Query failed"

CMSurfException
  Code:    1064
  Message: Query failed
  File:    /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/database/DBConnect.php
  Line:    192
  MySQL:   You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ') AND (`t1`.`navigation_id` = 0)' at line 4
  Query:   SELECT COUNT(*)
           FROM `praxis-seyler`.`widget_navigation` AS `t1`
           LEFT JOIN `widgets` AS `t2` ON (`t1`.`widget_id` = `t2`.`widget_id`)
           WHERE (`navigation_id` = ) AND (`t1`.`navigation_id` = 0)

  Trace:
  #0 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/database/SelectQuery.php(57): DBConnect->query()
  #1 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/abstract/AbstractContainerDAO.php(177): SelectQuery->fetchUnlimitedRowCount()
  #2 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/abstract/AbstractContainer.php(170): AbstractContainerDAO->read()
  #3 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/abstract/AbstractReferenceContainer.php(33): AbstractContainer->fill()
  #4 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/handler/FrontendHandler.php(1210): AbstractReferenceContainer->__construct()
  #5 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/handler/FrontendHandler.php(1232): FrontendHandler->fillWidgetCache()
  #6 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/handler/FrontendHandler.php(1251): FrontendHandler->getWidgets()
  #7 /var/www/vhosts/praxis-seyler.de/httpdocs/templates/praxis_seyler/template.php(48): FrontendHandler->renderWidgets()
  #8 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/handler/Template.php(133): include('/var/www/vhosts...')
  #9 /var/www/vhosts/praxis-seyler.de/httpdocs/admin/lib/handler/FrontendHandler.php(1557): Template->render()
  #10 /var/www/vhosts/praxis-seyler.de/httpdocs/index.php(53): FrontendHandler->render()
  #11 {main}