So all of a sudden, after a week of using it, I get an error message on my zabbix server gui (http://localhost/zabbix/.)
zabbix server
The error says: Zabbix serve
Zabbix serve
This may happen because of the old and new IP address I have faced same issue which was solve by below method:
vim /etc/zabbix/web/zabbix.conf.php $ZBX_SERVER = new ip address
then restart zabbix server