Another "I see this from time to time, and doing the following solves this for me": I sometimes see this when I've updated devstack a few times. I found getting rid of the (possibly stale) .pyc files in /opt/stack/horizon and restarting Apache is enough for the problem to go away.
Another "I see this from time to time, and doing the following solves this for me": I sometimes see this when I've updated devstack a few times. I found getting rid of the (possibly stale) .pyc files in /opt/stack/horizon and restarting Apache is enough for the problem to go away.