The following errors occur in the log when running

journalctl -u zabbix-server

Jan 21 16:18:03 uksilzab01 systemd[1]: Starting zabbix-server.service -  Zabbix Server...
Jan 21 16:18:03 uksilzab01 systemd[1]: Started zabbix-server.service - Zabbix Server.
Jan 21 16:18:04 uksilzab01 (sh)[9010]: zabbix-server.service: Referenced but unset environment variable evaluates to an empty string: MAINPID
Jan 21 16:18:04 uksilzab01 systemd[1]: zabbix-server.service: Control process exited, code=exited, status=1/FAILURE
Jan 21 16:18:04 uksilzab01 systemd[1]: zabbix-server.service: Failed with result 'exit-code'.

 

have check the config files are as before and that I can connect to the database with the credentials

The frontend is up correctly