openstack server create fails with nova.exception.GlanceConnectionFailed

Issue

Creating an instance on the overcloud fails with the following error:

(overcloud) [stack@undercloud ~]$ openstack server create --key-name test_key --image test_image --flavor test_flavor --network test_net test_vm
Unexpected API Error. Please report this at http://bugs.launchpad.net/nova/ and attach the Nova API log if possible.
<class 'nova.exception.GlanceConnectionFailed'> (HTTP 500) (Request-ID: req-xx-xx-xx-xx-xx)