Ubuntu – Oracle Database Express 11.2 job for oracle-xe.service failed

Environment:

• Ubuntu 14.04
• Oracle Database Express 11g Release 2

I'm receiving an error by starting service oracle-xe

systemctl status oracle-xe.service

● oracle-xe.service - LSB: Oracle 11g Express Edition
   Loaded: loaded (/etc/init.d/oracle-xe)
   Active: failed (Result: exit-code) since lun 2015-08-24 22:24:32 CEST; 18min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 12274 ExecStart=/etc/init.d/oracle-xe start (code=exited, status=1/FAILURE)

... systemd[1]: Starting LSB: Oracle 11g Express Edition...
... oracle-xe[12274]: Starting Oracle Net Listener.
... su[12282]: No passwd entry for user 'oracle'
... oracle-xe[12274]: Starting Oracle Database 11g Express Edition instance.
... su[12288]: No passwd entry for user 'oracle'
... oracle-xe[12274]: Failed to start Oracle Net Listener using /u01/app/oracle/product/11.2.0/xe/bin/tnslsnr and Oracle Express Database using /u01/app/oracle/product/11.2.0/xe/bin/sqlplus.
... systemd[1]: oracle-xe.service: control process exited, code=exited status=1
... systemd[1]: Failed to start LSB: Oracle 11g Express Edition.
... systemd[1]: Unit oracle-xe.service entered failed state.
... systemd[1]: oracle-xe.service failed.

I think that the problem could be with:
… su[12282]: No passwd entry for user 'oracle'

journalctl -xe

...
.. polkitd(authority=local)[641]: Registered Authentication Agent for unix-process:12249:680724 (system bus name :1.73 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale es_ES.UTF-8)
... systemd[1]: Starting LSB: Oracle 11g Express Edition...
-- Subject: Unit oracle-xe.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit oracle-xe.service has begun starting up.
... oracle-xe[12274]: Starting Oracle Net Listener.
... su[12282]: No passwd entry for user 'oracle'
... su[12282]: FAILED su for oracle by root
... su[12282]: - ??? root:oracle
... oracle-xe[12274]: Starting Oracle Database 11g Express Edition instance.
... su[12288]: No passwd entry for user 'oracle'
... su[12288]: FAILED su for oracle by root
... su[12288]: - ??? root:oracle
... oracle-xe[12274]: Failed to start Oracle Net Listener using /u01/app/oracle/product/11.2.0/xe/bin/tnslsnr and Oracle Express Database using /u01/app/oracle/product/11.2.0/xe/bin/sqlplus.
... systemd[1]: oracle-xe.service: control process exited, code=exited status=1
... systemd[1]: Failed to start LSB: Oracle 11g Express Edition.
-- Subject: Unit oracle-xe.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit oracle-xe.service has failed.
-- 
-- The result is failed.
... systemd[1]: Unit oracle-xe.service entered failed state.
... systemd[1]: oracle-xe.service failed.
... polkitd(authority=local)[641]: Unregistered Authentication Agent for unix-process:12249:680724 (system bus name :1.73, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale es_ES.UTF-8) (disconnected from bus)
... sudo[12248]: pam_unix(sudo:session): session closed for user root
... pkexec[12404]: pam_unix(polkit-1:session): session opened for user root by (uid=1000)
... pkexec[12404]: jose: Executing command [USER=root] [TTY=unknown] [CWD=/home/jose] [COMMAND=/usr/lib/update-notifier/package-system-locked]
... kernel: toshiba_acpi: Unknown key 120