While restarting PP service on linux, Tomcat can not start up, we see an error "Tomcat has not started yet. Operation timed out. Tomcat may still be trying to start".

Database is available, HUB comes up cleanly and so does PP Apache, but Tomcat doesn't (Web Port and Admin Portal). There's not much in the PP logs to point why Tomcat doesn't start. 

Probably some of you have any idea what to check and what could be the reason why server is down? Any ideas is highly appreciated!