Steps to reproduce:

1. Upgraded Zabbix from 5.0 to 6.0. OS is RHEL 8
2. Open Services page frtom Services menu. https://<url>/zabbix/zabbix.php?action=service.list

Result:

It shows blank where as in Zabbix 5.0 it was showing contents

Error in Frontend server log:

 [proxy_fcgi:error] [pid 302861:tid 140203821881088] [client 10.63.108.28:47571] AH01071: Got error 'PHP message: PHP Fatal error:  Uncaught TypeError: Argument 1 passed to CControllerServiceListGeneral::extendProblemEvents() must be of the type array, bool given, called in /usr/share/zabbix/app/controllers/CControllerServiceList.php on line 144 and defined in /usr/share/zabbix/app/controllers/CControllerServiceListGeneral.php:290\nStack trace:\n#0 /usr/share/zabbix/app/controllers/CControllerServiceList.php(144): CControllerServiceListGeneral::extendProblemEvents()\n#1 /usr/share/zabbix/include/classes/mvc/CController.php(479): CControllerServiceList->doAction()\n#2 /usr/share/zabbix/include/classes/core/ZBase.php(542): CController->run()\n#3 /usr/share/zabbix/include/classes/core/ZBase.php(222): ZBase->processRequest()\n#4 /usr/share/zabbix/include/config.inc.php(25): ZBase->run()\n#5 /usr/share/zabbix/zabbix.php(22): require_once('/usr/share/zabb...')\n#6 {main}\n  thrown in /usr/share/zabbix/app/controllers/CControllerServiceListGeneral.php on line 290', referer: https://scizabfe02.iserver.lan/zabbix/zabbix.php?action=dashboard.view