diff --git a/neutron/services/portforwarding/pf_plugin.py b/neutron/services/portforwarding/pf_plugin.py
index 0d82b12c73e..d5105085a26 100644
--- a/neutron/services/portforwarding/pf_plugin.py
+++ b/neutron/services/portforwarding/pf_plugin.py
@@ -31,6 +31,7 @@ from neutron_lib.exceptions import l3 as lib_l3_exc
 from neutron_lib.objects import exceptions as obj_exc
 from neutron_lib.plugins import constants
 from neutron_lib.plugins import directory
+from oslo_db import exception as oslo_db_exc
 from oslo_log import log as logging
 
 from neutron._i18n import _
@@ -402,7 +403,7 @@ class PortForwardingPlugin(fip_pf.PortForwardingPluginBase):
                 pf_obj.update_fields(port_forwarding, reset_changes=True)
                 self._check_port_forwarding_update(context, pf_obj)
                 pf_obj.update()
-        except obj_exc.NeutronDbObjectDuplicateEntry:
+        except oslo_db_exc.DBDuplicateEntry:
             (__, conflict_params) = self._find_existing_port_forwarding(
                 context, floatingip_id, pf_obj.to_dict())
             message = _("A duplicate port forwarding entry with same "
diff --git a/neutron/tests/unit/extensions/test_floating_ip_port_forwarding.py b/neutron/tests/unit/extensions/test_floating_ip_port_forwarding.py
index 634a7d17f62..3609d17385d 100644
--- a/neutron/tests/unit/extensions/test_floating_ip_port_forwarding.py
+++ b/neutron/tests/unit/extensions/test_floating_ip_port_forwarding.py
@@ -66,6 +66,21 @@ class FloatingIPPorForwardingTestCase(test_l3.L3BaseForIntTests,
 
         return fip_pf_req.get_response(self.ext_api)
 
+    def _update_fip_port_forwarding(self, fmt, floating_ip_id,
+                                    port_forwarding_id, **kwargs):
+        port_forwarding = {}
+        for k, v in kwargs.items():
+            port_forwarding[k] = v
+        data = {'port_forwarding': port_forwarding}
+
+        fip_pf_req = self._req(
+            'PUT', 'floatingips', data,
+            fmt or self.fmt, id=floating_ip_id,
+            sub_id=port_forwarding_id,
+            subresource='port_forwardings')
+
+        return fip_pf_req.get_response(self.ext_api)
+
     def test_create_floatingip_port_forwarding_with_port_number_0(self):
         with self.network() as ext_net:
             network_id = ext_net['network']['id']
@@ -100,3 +115,44 @@ class FloatingIPPorForwardingTestCase(test_l3.L3BaseForIntTests,
                     port['port']['fixed_ips'][0]['ip_address'],
                     port['port']['id'])
                 self.assertEqual(exc.HTTPBadRequest.code, res.status_int)
+
+    def test_update_floatingip_port_forwarding_with_dup_internal_port(self):
+        with self.network() as ext_net:
+            network_id = ext_net['network']['id']
+            self._set_net_external(network_id)
+            with self.subnet(ext_net, cidr='10.10.10.0/24'), \
+                    self.router() as router, \
+                    self.subnet(cidr='11.0.0.0/24') as private_subnet, \
+                    self.port(private_subnet) as port:
+                self._add_external_gateway_to_router(
+                    router['router']['id'],
+                    network_id)
+                self._router_interface_action(
+                    'add', router['router']['id'],
+                    private_subnet['subnet']['id'],
+                    None)
+                fip1 = self._make_floatingip(
+                    self.fmt,
+                    network_id)
+                self.assertIsNone(fip1['floatingip'].get('port_id'))
+                self._create_fip_port_forwarding(
+                    self.fmt, fip1['floatingip']['id'],
+                    2222, 22,
+                    'tcp',
+                    port['port']['fixed_ips'][0]['ip_address'],
+                    port['port']['id'])
+                fip2 = self._make_floatingip(
+                    self.fmt,
+                    network_id)
+                fip_pf_response = self._create_fip_port_forwarding(
+                    self.fmt, fip2['floatingip']['id'],
+                    2222, 23,
+                    'tcp',
+                    port['port']['fixed_ips'][0]['ip_address'],
+                    port['port']['id'])
+                update_res = self._update_fip_port_forwarding(
+                    self.fmt, fip2['floatingip']['id'],
+                    fip_pf_response.json['port_forwarding']['id'],
+                    **{'internal_port': 22})
+                self.assertEqual(exc.HTTPBadRequest.code,
+                                 update_res.status_int)