Communication error with the OPMN server local port

I ran into an interesting problem the other day when trying to start OBIEE components via OPMN. I kept getting the following message:

“Communication error with the OPMN server local port”

After a lot of head scratching I figured out that somehow OPMN had been started as root user (this was a Unix system) rather than the application installer/owner. I was able to confirm this by running the following command which also gave the PIDs in order to kill the processes (there will be two of them):

ps -ef | grep 'opmn -d' | grep -v 'grep'

I hope this helps someone else in the same situation.