I have the same experience when install openstack . when I install sync DB and perform su -s /bin/sh -c "keystone-manage db_sync". Once you performance those command ,
User –uroot –p root XXX(XXX indicate your DB password,
login DB, then perform use keystone ; show tables.
If you can see the following ,
show tables;
+------------------------+
| Tables_in_keystone |
+------------------------+
| access_token |
| assignment |
| config_register |
| consumer |
| credential |
| domain |
| endpoint |
| endpoint_group |
| federation_protocol |
| group |
| id_mapping |
| identity_provider |
| idp_remote_ids |
| mapping |
| migrate_version |
| policy |
| policy_association |
| project |
| project_endpoint |
| project_endpoint_group |
| region |
| request_token |
| revocation_event |
| role |
| sensitive_config |
| service |
| service_provider |
| token |
| trust |
| trust_role |
| user |
| user_group_membership |
| whitelisted_config |
+------------------------+
33 rows in set (0.00 sec)
That is saying, you can ignore the error.