In openstack-ocata, when install the neutron, I want to restart the neutronpserver.service.

systemctl restart neutron-server.service

But I get the error:

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

So I use the:

journalctl -xe

to see the detail:

Jun 01 01:37:29 controller1 neutron-server[94446]: Could not load neutron.openstack.common.notifier.rpc_notifier
Jun 01 01:37:31 controller1 systemd[1]: neutron-server.service: main process exited, code=exited, status=1/FAILURE
Jun 01 01:37:31 controller1 systemd[1]: Failed to start OpenStack Neutron Server.
-- Subject: Unit neutron-server.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit neutron-server.service has failed.
-- 
-- The result is failed.
Jun 01 01:37:31 controller1 systemd[1]: Unit neutron-server.service entered failed state.
Jun 01 01:37:31 controller1 systemd[1]: neutron-server.service failed.
Jun 01 01:37:31 controller1 systemd[1]: neutron-server.service holdoff time over, scheduling restart.
Jun 01 01:37:31 controller1 systemd[1]: Starting OpenStack Neutron Server...
-- Subject: Unit neutron-server.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit neutron-server.service has begun starting up.
Jun 01 01:37:32 controller1 neutron-server[94460]: Guru meditation now registers SIGUSR1 and SIGUSR2 by default for backward compatibility. SIGUSR1 will no longer be registered in
Jun 01 01:37:33 controller1 neutron-server[94460]: Option "verbose" from group "DEFAULT" is deprecated for removal.  Its value may be silently ignored in the future.
Jun 01 01:37:33 controller1 neutron-server[94460]: Option "notification_driver" from group "DEFAULT" is deprecated. Use option "driver" from group "oslo_messaging_notifications".
Jun 01 01:37:33 controller1 neutron-server[94460]: Could not load neutron.openstack.common.notifier.rpc_notifier
Jun 01 01:37:35 controller1 systemd[1]: neutron-server.service: main process exited, code=exited, status=1/FAILURE
Jun 01 01:37:35 controller1 systemd[1]: Failed to start OpenStack Neutron Server.
-- Subject: Unit neutron-server.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit neutron-server.service has failed.
-- 
-- The result is failed.
Jun 01 01:37:35 controller1 systemd[1]: Unit neutron-server.service entered failed state.
Jun 01 01:37:35 controller1 systemd[1]: neutron-server.service failed.

Someone know what's wrong with that?