Serviio 1.5.2 - OS X 10.11 El Capitan Beta
When I attempted to load the console to start it, the error “Cannot connect to Serviio server, it does not seem to be running. Exiting…” was received. When I attempted to use the command in Terminal to start the server, the error received was “/Library/LaunchDaemons/org.serviio.server.plist: service already loaded”. On each reboot I had to use the "Stop Server" terminal command, then follow up with the command to start the server in order for it to be active and able to launch the console. Reinstallation had no effect.
What eventually seemed to help is disabling the new OS X security feature of "System Integrity Protection", then restarting. So far it appears to be working after several reboots.
So if anyone runs into this problem when they update to the full production version of El Capitan, this may be a possible fix for them.