I am running Icehouse version of Openstack on Ubuntu 14.04. After updating Openstack services to version 2014.1.5 I started seeing error message on Horizon: Error: Unable to connect to Neutron.

The error message appears only on the Instances page and VNC-connection page. The are not any error logged to Neutron logs nor in Apache2/Horizon log. All Neutron services are running. Everything seems to be working on the dashboard despite this error message. I can create and delete instances, networks, routers etc... All Neutron command line commands work without problem.

This happens on multiple different installation of Openstack.

Since everything seems to working I guess this error message should not be displayed at all. Altough nothing id broken it very annnoying to see this error every time I open Horizon. So how could I troubleshoot this futher or fix it?

More info:

root@openstack:~# ps -ef  | grep neutron*
neutron  13301     1  0 Jul27 ?        00:04:07 /usr/bin/python /usr/bin/neutron-server --config-file /etc/neutron/neutron.conf --log-file /var/log/neutron/server.log --config-file /etc/neutron/plugins/ml2/ml2_conf.ini
neutron  13352     1  0 Jul27 ?        00:03:19 /usr/bin/python /usr/bin/neutron-openvswitch-agent --config-file=/etc/neutron/neutron.conf --config-file=/etc/neutron/plugins/ml2/ml2_conf.ini --log-file=/var/log/neutron/openvswitch-agent.log
neutron  13373     1  0 Jul27 ?        00:01:01 /usr/bin/python /usr/bin/neutron-l3-agent --config-file=/etc/neutron/neutron.conf --config-file=/etc/neutron/l3_agent.ini --config-file=/etc/neutron/fwaas_driver.ini --log-file=/var/log/neutron/l3-agent.log
neutron  13397     1  0 Jul27 ?        00:00:16 /usr/bin/python /usr/bin/neutron-dhcp-agent --config-file=/etc/neutron/neutron.conf --config-file=/etc/neutron/dhcp_agent.ini --log-file=/var/log/neutron/dhcp-agent.log
neutron  13542     1  0 Jul27 ?        00:00:10 /usr/bin/python /usr/bin/neutron-metadata-agent --config-file=/etc/neutron/neutron.conf --config-file=/etc/neutron/metadata_agent.ini --log-file=/var/log/neutron/metadata-agent.log
root     13590 13352  0 Jul27 ?        00:00:00 sudo /usr/bin/neutron-rootwrap /etc/neutron/rootwrap.conf ovsdb-client monitor Interface name,ofport --format=json
root     13592 13590  0 Jul27 ?        00:00:00 /usr/bin/python /usr/bin/neutron-rootwrap /etc/neutron/rootwrap.conf ovsdb-client monitor Interface name,ofport --format=json
root     17540 23152  0 09:53 pts/2    00:00:00 grep --color=auto neutron*
root     18358     1  0 Jul27 ?        00:00:00 /usr/bin/python /usr/bin/neutron-ns-metadata-proxy --pid_file=/var/lib/neutron/external/pids/656940e3-c0c1-453f-b3df-2733f4dc2c4b.pid --metadata_proxy_socket=/var/lib/neutron/metadata_proxy --router_id=656940e3-c0c1-453f-b3df-2733f4dc2c4b --state_path=/var/lib/neutron --metadata_port=9697 --log-file=neutron-ns-metadata-proxy-656940e3-c0c1-453f-b3df-2733f4dc2c4b.log --log-dir=/var/log/neutron
nobody   20259     1  0 Jul27 ?        00:00:00 dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tape68a2015-64 --except-interface=lo --pid-file=/var/lib/neutron/dhcp/3d00b23f-ca7a-4860-b2fa-213e27cc41d0/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/3d00b23f-ca7a-4860-b2fa-213e27cc41d0/host --addn-hosts=/var/lib/neutron/dhcp/3d00b23f-ca7a-4860-b2fa-213e27cc41d0/addn_hosts --dhcp-optsfile=/var/lib/neutron/dhcp/3d00b23f-ca7a-4860-b2fa-213e27cc41d0/opts --dhcp-leasefile=/var/lib/neutron/dhcp/3d00b23f-ca7a-4860-b2fa-213e27cc41d0/leases --dhcp-range=set:tag0,10.100.100.0,static,86400s --dhcp-lease-max=256 --conf-file= --domain=openstacklocal

root@openstack:~# neutron agent-list
+--------------------------------------+--------------------+-------+-------+----------------+
| id                                   | agent_type         | host  | alive | admin_state_up |
+--------------------------------------+--------------------+-------+-------+----------------+
| 74b06b71-a3fa-4567-9395-be6b1e427d50 | DHCP agent         | fsd25 | :-)   | True           |
| 77113f11-7eff-4987-b51e-de40238c25dc | Open vSwitch agent | fsd25 ...