During the openstack installation first basic setup is to create hostname entries for controller, network and compute nodes. When you create an instance on your openstack and using openstack dashboard and try to connect newly created instance via console and you hit this error.

Reason is  your openstack machines running on different machine and you are accessing dashboard on different machine  when you don't have hostname entry for compute node, i mean you can ping your compute node via ip but not hostname(unless you have dns name, if you have that you wouldn't have hit this error).

Now observe below picture, i have create one instance and at console tab.


URL is 192.168.56.10 my compute nodes address, running some where in my lan, but horizon is trying to access console of the instance using hostname you can see url at the backend, if you want to see it, click on "Click here to show only console" link which i highlighted, then you'll come know what was the issue. Check this screen shot.


see ??? this url says "controller", which is my controller node.  

Quick Fix:

To resolve this quickly replace "controller" with you controller node's ip, then you'll see instance's console.

Note: Dont remove any colun.

Permanent Fix:

Edit nova.conf on compute node and replace controller's hostname with paddles at vnc connection.
Open /etc/nova/nova.conf and search for 
novncproxy_base_url = http://controller:6080/vnc_auto.html
and modify it to 
novncproxy_base_url = http://192.168.56.10:6080/vnc_auto.html
Note: 192.168.56.10 is my controller's ip address and you use your controller's ip.

Finally restart nova compute service
root@compute1:~# service nova-compute restart
nova-compute stop/waiting
nova-compute start/running, process 12094
root@compute1:~#
now go to dashboard refresh it and try to access your instance's console. Now you should see console url with ip address instead of hostname.

gil ...