Getting this "Zabbix server is not running" onto my Zabbix webpage.

It's running on a Debian 9 machine, with his database on a CentOS 7 (external).

When I check the status of it's service, I get the message: "

zabbix-server.service - Zabbix Server
Loaded: loaded (/lib/systemd/system/zabbix-server.service; enabled; vendor preset: enabled)
Active: active (running) since Mon 2018-04-30 10:11:16 -03; 22s ago
Process: 1931 ExecStop=/bin/kill -SIGTERM $MAINPID (code=exited, status=0/SUCCESS)
Process: 1934 ExecStart=/usr/sbin/zabbix_server -c $CONFFILE (code=exited, status=0/SUCCESS)
Main PID: 1936 (zabbix_server)
Tasks: 1 (limit: 9830)
CGroup: /system.slice/zabbix-server.service
└─1936 /usr/sbin/zabbix_server -c /etc/zabbix/zabbix_server.conf

abr 30 10:11:16 PSS-APP03 systemd[1]: Starting Zabbix Server...
abr 30 10:11:16 PSS-APP03 systemd[1]: zabbix-server.service: PID file /run/zabbix/zabbix_server.pid not readable (yet?) after start: No such file or directory
abr 30 10:11:16 PSS-APP03 systemd[1]: Started Zabbix Server.

"