If you configured a vCenter Server Appliance 5.x to send log files to a third-party Syslog target and then upgraded to version 6.0, log files stop being forwarded after the upgrade.
Restart the vmware-syslog and vmware-syslog-health services after the upgrade to enable redirection of log files to previously configured Syslog target. You can use the vSphere Web Client or the vCenter Server Appliance console.
To restart the service through the vSphere Web Client:
Restart through the vCenter Server Appliance console