Comment 3 for bug 1929633

It's happening in our CI. We're still using zuulv2 + jenkins + devstack-gate for CI jobs although we're working on migrating to latest zuul but not done yet.
Attached is our local.conf, please take a look if there's any misconfig.

Though I'm not sure why this issue happens, I think we'd better add a check before calling 'self._sb_ovn.chassis_exists' in https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py#L656
some patch like this:
===============================
diff --git a/neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py b/neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py
index 229ea0f85b..2c129179f9 100644
--- a/neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py
+++ b/neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py
@@ -653,7 +653,8 @@ class OVNMechanismDriver(api.MechanismDriver):
                       port['id'])
             return False

- if not self._sb_ovn.chassis_exists(host):
+ if (hasattr(self._sb_ovn, 'chassis_exists') and
+ not self._sb_ovn.chassis_exists(host)):
             LOG.debug('No provisioning block for port %(port_id)s since no '
                       'OVN chassis for host: %(host)s',
                       {'port_id': port['id'], 'host': host})
===============================

thanks and regards
Sam