O servidor Apache não inicia no CentOS

Question

Estou tentando instalar o certificado ssl em uma nova máquina linode com o centos 7. Instalei o httpd e o open_ssl. Eu segui este guia para o apache: link

E este link para criar um certificado ssl.

Agora, quando tento reiniciar o apache com este comando:

systemctl restart httpd.service

Eu recebi este erro:

Job for httpd.service failed because the control process exited with error code. See "systemctl status httpd.service" and "journalctl -xe" for details.

Se eu executar o primeiro script, recebo este:

httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Wed 2017-03-01 16:32:27 UTC; 48s ago
     Docs: man:httpd(8)
           man:apachectl(8)
  Process: 13836 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=1/FAILURE)
  Process: 13835 ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND (code=exited, status=1/FAILURE)
 Main PID: 13835 (code=exited, status=1/FAILURE)

Mar 01 16:32:27 li947-5 systemd[1]: Starting The Apache HTTP Server...
Mar 01 16:32:27 li947-5 systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
Mar 01 16:32:27 li947-5 kill[13836]: kill: cannot find process ""
Mar 01 16:32:27 li947-5 systemd[1]: httpd.service: control process exited, code=exited status=1
Mar 01 16:32:27 li947-5 systemd[1]: Failed to start The Apache HTTP Server.
Mar 01 16:32:27 li947-5 systemd[1]: Unit httpd.service entered failed state.
Mar 01 16:32:27 li947-5 systemd[1]: httpd.service failed.

e se eu rodar "journalctl -xe" eu recebo isto:

 -- Subject: Unit httpd.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit httpd.service has failed.
--
-- The result is failed.
Mar 01 16:26:00 li947-5 systemd[1]: Unit httpd.service entered failed state.
Mar 01 16:26:00 li947-5 polkitd[3179]: Unregistered Authentication Agent for unix-process:4730:177180 (system bus name :1.35, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (dis
Mar 01 16:26:00 li947-5 systemd[1]: httpd.service failed.
Mar 01 16:30:01 li947-5 systemd[1]: Started Session 6 of user root.
-- Subject: Unit session-6.scope has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit session-6.scope has finished starting up.
--
-- The start-up result is done.
Mar 01 16:30:01 li947-5 systemd[1]: Starting Session 6 of user root.
-- Subject: Unit session-6.scope has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit session-6.scope has begun starting up.
Mar 01 16:30:01 li947-5 CROND[4746]: (root) CMD (/usr/lib64/sa/sa1 1 1)
Mar 01 16:31:01 li947-5 anacron[4602]: Job 'cron.daily' started
Mar 01 16:31:01 li947-5 run-parts(/etc/cron.daily)[4753]: starting logrotate
Mar 01 16:31:01 li947-5 run-parts(/etc/cron.daily)[4758]: finished logrotate
Mar 01 16:31:01 li947-5 run-parts(/etc/cron.daily)[4760]: starting man-db.cron
Mar 01 16:31:13 li947-5 run-parts(/etc/cron.daily)[13828]: finished man-db.cron
Mar 01 16:31:13 li947-5 anacron[4602]: Job 'cron.daily' terminated
Mar 01 16:32:27 li947-5 polkitd[3179]: Registered Authentication Agent for unix-process:13829:215883 (system bus name :1.38 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org/freedesktop/PolicyKit1
Mar 01 16:32:27 li947-5 systemd[1]: Starting The Apache HTTP Server...
-- Subject: Unit httpd.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit httpd.service has begun starting up.
Mar 01 16:32:27 li947-5 systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
Mar 01 16:32:27 li947-5 kill[13836]: kill: cannot find process ""
Mar 01 16:32:27 li947-5 systemd[1]: httpd.service: control process exited, code=exited status=1
Mar 01 16:32:27 li947-5 systemd[1]: Failed to start The Apache HTTP Server.
-- Subject: Unit httpd.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit httpd.service has failed.
--
-- The result is failed.
Mar 01 16:32:27 li947-5 systemd[1]: Unit httpd.service entered failed state.
Mar 01 16:32:27 li947-5 systemd[1]: httpd.service failed.
Mar 01 16:32:27 li947-5 polkitd[3179]: Unregistered Authentication Agent for unix-process:13829:215883 (system bus name :1.38, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (di
l

Eu tentei pesquisar o problema, mas sem sucesso. Alguém sabe como resolver isso?