diff --git a/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py b/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py
index 17991a8c410..279f662e002 100644
--- a/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py
+++ b/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py
@@ -504,6 +504,9 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
             LOG.warning("Can't update segmentation id on no uniq segment "
                         "for a network %s", network['id'])
             return
+        except vlanmanager.MappingNotFound:
+            LOG.debug("Mapping not found for network %s", network['id'])
+            return
 
         if segmentation_id_old is None:
             # The segmentation id did not changed.
diff --git a/neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py b/neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py
index 06efeabcf42..6ce4558d834 100644
--- a/neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py
+++ b/neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py
@@ -2717,6 +2717,15 @@ class TestOvsNeutronAgent(object):
             self.agent._update_network_segmentation_id(network)
             mock_get.assert_not_called()
 
+    def test__update_network_segmentation_id_mapping_not_found(self):
+        network = {'id': 'my-net-uuid',
+                   'segments': [mock.ANY]}
+        with mock.patch.object(self.agent.vlan_manager,
+                               'get') as mock_get:
+            mock_get.side_effect = ValueError
+            self.assertIsNone(
+                self.agent._update_network_segmentation_id(network))
+
     def _test_treat_smartnic_port(self, vif_type):
         vm_uuid = "407a79e0-e0be-4b7d-92a6-513b2161011b"
         iface_id = "407a79e0-e0be-4b7d-92a6-513b2161011c"