• Fail to start Tomcat service following up the installation steps in the installation guide
• No log files are generated under Tomcat's log folder
• Get below return message when using the command: sudo service tomcat9.0 start

  Job for tomcat9.0.service failed because a timeout was exceeded.
  See "systemctl status tomcat9.0.service" and "journalctl -xeu tomcat9.0.service" for details.

• Using journalctl -xeu command, it shows the below message:

####-virtual-machine systemd[1]: /etc/systemd/system/tomcat9.0.service:7: PIDFile= references a path below legacy directory /var/run/, updating /var/run/tomcat.pid → /run/tomcat.pid; pl>
####-virtual-machine systemd[1]: /etc/systemd/system/tomcat9.0.service:14: Ignoring unknown escape sequences: "\"
####-virtual-machine systemd[1]: /etc/systemd/system/tomcat9.0.service:29: Unknown key name '-Dcatalina.home' in section 'Service', ignoring.
####-virtual-machine systemd[1]: /etc/systemd/system/tomcat9.0.service:7: PIDFile= references a path below legacy directory /var/run/, updating /var/run/tomcat.pid → /run/tomcat.pid; pl>
####-virtual-machine systemd[1]: /etc/systemd/system/tomcat9.0.service:14: Ignoring unknown escape sequences: "\"
####-virtual-machine systemd[1]: /etc/systemd/system/tomcat9.0.service:29: Unknown key name '-Dcatalina.home' in section 'Service', ignoring.
####-virtual-machine systemd[1]: Starting Apache Tomcat Web Application Container...
   Subject: A start job for unit tomcat9.0.service has begun execution
   Defined-By: systemd
   Support: http://www.ubuntu.com/support
   
   A start job for unit tomcat9.0.service has begun execution.
   
   The job identifier is 4126.
####-virtual-machine systemd[1]: tomcat9.0.service: Can't open PID file /run/tomcat.pid (yet?) after start: Operation not permitted
####-virtual-machine systemd[1]: tomcat9.0.service: start operation timed out. Terminating.
####-virtual-machine systemd[1]: tomcat9.0.service: Failed with result 'timeout'.
Subject: Unit failed
Defined-By: systemd
Support: http://www.ubuntu.com/support

The unit tomcat9.0.service has entered the 'failed' state with result 'timeout'.