Error when starting fms: "A copy of the Catalyst is already running from the installation" (4311283)

When we try to start fms , get the following error:
YYYY-MM-DD HH:MM:SS.SSS FATAL [native] A copy of the Catalyst is already running from the installation in /opt/FogLight. Only one copy of the Catalyst can be run from this installation directory at any one time.

and when we run fms -q, get the following:
YYYY-MM-DD HH:MM:SS.SSS ERROR [native] Could not send kill signal to process Foglight: No such process

The fms has shut down incompletely, or crashed, and has not cleaned up as per it's normal shutdown routine.

WORKAROUND:

1. Check your Windows Services or if on a UNIX box, run the following command from your server to confirm that the fms isn't running: ps -ef | grep -i Foglight

2. If you do see the Foglight Management Server process there, check $FGLHOME/state folder for these two hidden files:
.Foglight-[hostname].pid
.QcnProcessRunner-[hostname].pid

On UNIX it's a hidden file so ls -la will show you exactly what the filename is on your server). If the PID in this file doesn't match what you see running, you should kill the process, and remove these .pid files.

3. If you see no processes running, you can remove the .pid files and that should allow you to properly start the server again.