Steps to reproduce:

1. Changes in configuration: CacheSize=16M
2. Reload zabbix-server service: service zabbix-server restart
3. Then restart daemons systemctl daemon-reload
4. See status of zabbix-server: journalctl -xe
5. PidFile unavailable
6. Change PidFalue in zabbix-server.service and inf the conf file to make them match eachother
7. Reload zabbix-server service: service zabbix-server restart
8. Then restart daemons systemctl daemon-reload
9. See status of zabbix-server: journalctl -xe
10. /usr/lib/systemd/system/zabbix-server.service:22 Unkown lvalue 'PidFile' in section 'Service'

Result:
See error screenshot, .service file attached too