OpenStack Horizon Error: Unable to get network agents info

OpenStack Dashboard Error: Unable to get network agents info often seen in Horizon is a result of Neutron related problems.

Usually the problem is caused by neutron-service failure due to service operation time outs.

The below screenshot presents OpenStack Dashboard Error: Unable to get network agents info:

Steps to fix OpenStack Error: Unable to get network agents info:

1. Verify neutron-server status

[root@controller ~(keystone_admin)]# systemctl status neutron-server
● neutron-server.service - OpenStack Neutron Server
   Loaded: loaded (/usr/lib/systemd/system/neutron-server.service; enabled; vendor preset: disabled)
   Active: failed (Result: timeout) since Sat 2016-08-13 19:37:39 CEST; 32min ago
  Process: 805 ExecStart=/usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/plugin.ini --config-dir /etc/neutron/conf.d/common --config-dir /etc/neutron/conf.d/neutron-server --log-file /var/log/neutron/server.log (code=killed, signal=TERM)
 Main PID: 805 (code=killed, signal=TERM)

Aug 13 19:36:09 controller systemd[1]: Starting OpenStack Neutron Server...
Aug 13 19:37:39 controller systemd[1]: neutron-server.service start operation timed out. Terminating.
Aug 13 19:37:39 controller systemd[1]: Failed to start OpenStack Neutron Server.
Aug 13 19:37:39 controller systemd[1]: Unit neutron-server.service entered failed state.
Aug 13 19:37:39 controller systemd[1]: neutron-server.service failed.

[root@controller ~(keystone_admin)]# openstack-status | grep neutron-server
neutron-server:                         failed

neutron-server service entered failed state due to operation time out.

2. Restart neutron-server service

[root@controller ~(keystone_admin)]# systemctl restart neutron-server

3. Verify neutron-server status after restart

[root@controller ~(keystone_admin)]# systemctl status neutron-server
● neutron-server.service - OpenStack Neutron Server
   Loaded: loaded (/usr/lib/systemd/system/neutron-server.service; enabled; vendor preset: disabled)
   Active: active (running) since Sat 2016-08-13 20:10:43 CEST; 8s ago
 Main PID: 4572 (neutron-server)
   CGroup: /system.slice/neutron-server.service
           ├─4572 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           ├─4585 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           ├─4586 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           ├─4587 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           ├─4588 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           ├─4589 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           ├─4590 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           ├─4591 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           ├─4592 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...
           └─4593 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /...

Aug 13 20:10:32 controller systemd[1]: Starting OpenStack Neutron Server...
Aug 13 20:10:33 controller neutron-server[4572]: Guru mediation now registers SIGUSR1 and SIGUSR2 by default for backward compatibility. SIGUSR1 will no longer be registered in a future relea...rate reports.
Aug 13 20:10:35 controller neutron-server[4572]: Option "verbose" from group "DEFAULT" is deprecated for removal.  Its value may be silently ignored in the future.
Aug 13 20:10:38 controller neutron-server[4572]: Option "notification_driver" from group "DEFAULT" is deprecated. Use option "driver" from group "oslo_messaging_notifications".
Aug 13 20:10:43 controller systemd[1]: Started OpenStack Neutron Server.
Hint: Some lines were ellipsized, use -l to show in full.

[root@controller ~(keystone_admin)]# openstack-status | grep neutron-server
neutron-server:                         active

neutron-server is now active and fully operational.