After running apt-get update / upgrade and Jenkins is updated from 2.13 to 2.14 by the package, it failed to start.
I have also noticed this in previous 2.x upgrades as well. After I reboot my system, it loads correctly.
sudo systemctl status jenkins.service
● jenkins.service - LSB: Start Jenkins at boot time
Loaded: loaded (/etc/init.d/jenkins)
Active: failed (Result: exit-code) since Tue 2016-07-19 05:58:50 EDT; 41s ago
Process: 2079 ExecStop=/etc/init.d/jenkins stop (code=exited, status=0/SUCCESS )
Process: 2120 ExecStart=/etc/init.d/jenkins start (code=exited, status=7)
su: Successful su for jenkins by root
su: + ??? root:jenkins
su: pam_unix(su:session): session opened for u...0)
jenkins: Starting Jenkins Continuous Integrati...d!
systemd: jenkins.service: control process exited,...=7
systemd: Failed to start LSB: Start Jenkins at bo...e.
systemd: Unit jenkins.service entered failed state.