Using ClusterWS with pm2. PIDs undefined.

[Napzu]

I am trying to use ClusterWS with pm2.

Starting server with node server.js all works fine.

But starting with pm2 start server.js and checking with pm2 monit what's going on, I get never ending log of:
server > Broker PID undefined has been restarted
server > Worker PID undefined has been restarted
server > Broker PID undefined has been restarted
server > Worker PID undefined has been restarted
server > Broker PID undefined has been restarted
server > Worker PID undefined has been restarted