Upgrading Horizon

On your Horizon host:

yum upgrade \*horizon\* \*openstack-dashboard\*

Fixing local_settings

The Horizon configuration file (/etc/openstack-dashboard/local_settings) has changed substantially between versions, so you will need to:

Back up your existing local_settings file.
Replace local_settings with local_settings.rpmnew
Update your new local_settings file with any necessary information from your old configuration (such as SECRET_KEY, OPENSTACK_HOST, etc).

If you are running Django 1.5 (or later), you will need to make sure that there is a correctly configured ALLOWED_HOSTS setting in your local_settings file. ALLOWED_HOSTS is a list hostnames that can be used to contact your Horizon service; if people will be accessing Horizon as "http://dashboard.example.com", you would set:

ALLOWED_HOSTS=['dashboard.example.com']

If you are running Horizon on your local system, you might want:

ALLOWED_HOSTS=['localhost']

If people will be using ip addresses instead of (or in addition to) hostnames, you could do something like:

ALLOWED_HOSTS=['dashboard.example.com', '192.168.122.200']

You can read more about the ALLOWED_HOSTS setting in the Django documentation.