zabbix4.0 zabbix-server.service never wrote its PID file. Failing.

CentOS7.6启动Zabbix4.0时，报出如下错误（错误没保存，从网上其他位置复制而来）：

[root@iZuf6fdluqx20hmkk68ndfZ zabbix]# systemctl start zabbix-server
Job for zabbix-server.service failed because a configured resource limit was exceeded. See "systemctl status zabbix-server.service" and "journalctl -xe" for details.
[root@iZuf6fdluqx20hmkk68ndfZ zabbix]# journalctl -xe
--
-- Unit zabbix-server.service has begun starting up.
Apr 18 22:21:06 localhost.localdomain systemd[1]: PID file /run/zabbix/zabbix_server.pid not readable (yet?) after start.
Apr 18 22:21:06 localhost.localdomain systemd[1]: zabbix-server.service never wrote its PID file. Failing.
Apr 18 22:21:06 localhost.localdomain systemd[1]: Failed to start Zabbix Server.
-- Subject: Unit zabbix-server.service has failed

试了几种办法没有解决，最终重启服务器解决。