diff --git a/neutron/agent/common/ovsdb_monitor.py b/neutron/agent/common/ovsdb_monitor.py
index a6d71665af1..a3a575568d3 100644
--- a/neutron/agent/common/ovsdb_monitor.py
+++ b/neutron/agent/common/ovsdb_monitor.py
@@ -16,6 +16,7 @@ from oslo_log import log as logging
 from oslo_serialization import jsonutils
 
 from neutron.agent.common import async_process
+from neutron.agent.common import ovs_lib
 from neutron.agent.ovsdb import api as ovsdb
 from neutron.agent.ovsdb.native import helpers
 from neutron.common import utils
@@ -108,6 +109,11 @@ class SimpleInterfaceMonitor(OvsdbMonitor):
                     external_ids = ovsdb.val_to_py(external_ids)
                 if ofport:
                     ofport = ovsdb.val_to_py(ofport)
+                if ofport == ovs_lib.INVALID_OFPORT:
+                    LOG.debug("Ofport of port %(name)s is %(ofport)s. "
+                              "Skipping its event.",
+                              {'name': name, 'ofport': ofport})
+                    continue
                 device = {'name': name,
                           'ofport': ofport,
                           'external_ids': external_ids}
diff --git a/neutron/tests/unit/agent/common/test_ovsdb_monitor.py b/neutron/tests/unit/agent/common/test_ovsdb_monitor.py
index fc645ee61d9..71043b18021 100644
--- a/neutron/tests/unit/agent/common/test_ovsdb_monitor.py
+++ b/neutron/tests/unit/agent/common/test_ovsdb_monitor.py
@@ -85,3 +85,12 @@ class TestSimpleInterfaceMonitor(base.BaseTestCase):
             self.monitor.process_events()
             self.assertEqual(self.monitor.new_events['added'][0]['ofport'],
                              ovs_lib.UNASSIGNED_OFPORT)
+
+    def process_event_invalid_of_port(self):
+        output = '{"data":[["e040fbec-0579-4990-8324-d338da33ae88","insert",'
+        output += '"m50",-1,["map",[]]]],"headings":["row","action",'
+        output += '"name","ofport","external_ids"]}'
+        with mock.patch.object(
+                self.monitor, 'iter_stdout', return_value=[output]):
+            self.monitor.process_events()
+            self.assertEqual([], self.monitor.new_events['added'])