Comment 1 for bug 1538896

I was able to reproduce this, stack trace pasted below from nova logs:

2016-02-04 23:49:50.052 DEBUG nova.api.openstack.wsgi [req-314f0442-98f4-4cd6-8cc1-3b75fb09ed3f admin admin] Calling method '<bound method FlavorExtraSpecsController.index of <nova.api.openstack.compute.flavors_extraspecs.FlavorExtraSpecsController object at 0x7ff5c513d690>>' from (pid=27806) _process_stack /opt/stack/nova/nova/api/openstack/wsgi.py:699
2016-02-04 23:49:50.064 ERROR nova.api.openstack.extensions [req-314f0442-98f4-4cd6-8cc1-3b75fb09ed3f admin admin] Unexpected exception in API method
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions Traceback (most recent call last):
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions File "/opt/stack/nova/nova/api/openstack/extensions.py", line 478, in wrapped
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions return f(*args, **kwargs)
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions File "/opt/stack/nova/nova/api/openstack/compute/flavors_extraspecs.py", line 60, in index
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions return self._get_extra_specs(context, flavor_id)
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions File "/opt/stack/nova/nova/api/openstack/compute/flavors_extraspecs.py", line 39, in _get_extra_specs
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions flavor = common.get_flavor(context, flavor_id)
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions File "/opt/stack/nova/nova/api/openstack/common.py", line 543, in get_flavor
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions raise exc.HTTPNotFound(explanation=error.format_message())
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions HTTPNotFound: Flavor 10 could not be found.
2016-02-04 23:49:50.064 TRACE nova.api.openstack.extensions
2016-02-04 23:49:50.065 INFO nova.api.openstack.wsgi [req-314f0442-98f4-4cd6-8cc1-3b75fb09ed3f admin admin] HTTP exception thrown: Unexpected API Error. Please report this at http://bugs.launchpad.net/nova/ and attach the Nova API log if possible.
<class 'webob.exc.HTTPNotFound'>
2016-02-04 23:49:50.065 DEBUG nova.api.openstack.wsgi [req-314f0442-98f4-4cd6-8cc1-3b75fb09ed3f admin admin] Returning 500 to user: Unexpected API Error. Please report this at http://bugs.launchpad.net/nova/ and attach the Nova API log if possible.
<class 'webob.exc.HTTPNotFound'> from (pid=27806) __call__ /opt/stack/nova/nova/api/openstack/wsgi.py:1070
2016-02-04 23:49:50.066 INFO nova.osapi_compute.wsgi.server [req-314f0442-98f4-4cd6-8cc1-3b75fb09ed3f admin admin] 10.42.0.53 "GET /v2.1/9f087ae0a9784a1a925d8cc428d0b151/flavors/10/os-extra_specs HTTP/1.1" status: 500 len: 499 time: 0.1468120