diff --git a/neutron/api/v2/base.py b/neutron/api/v2/base.py
index 30c4c1c56db..84f9cb05ed7 100644
--- a/neutron/api/v2/base.py
+++ b/neutron/api/v2/base.py
@@ -593,7 +593,8 @@ class Controller(object):
 
     @db_api.retry_db_errors
     def _update(self, request, id, body, **kwargs):
-        body = Controller.prepare_request_body(request.context, body, False,
+        body = Controller.prepare_request_body(request.context,
+                                               copy.deepcopy(body), False,
                                                self._resource, self._attr_info,
                                                allow_bulk=self._allow_bulk)
         action = self._plugin_handlers[self.UPDATE]
diff --git a/neutron/tests/unit/extensions/test_l3_ext_gw_mode.py b/neutron/tests/unit/extensions/test_l3_ext_gw_mode.py
index 3413667aa46..a6423c4da90 100644
--- a/neutron/tests/unit/extensions/test_l3_ext_gw_mode.py
+++ b/neutron/tests/unit/extensions/test_l3_ext_gw_mode.py
@@ -17,6 +17,7 @@
 import mock
 from neutron_lib import constants
 from oslo_config import cfg
+from oslo_db import exception as db_exc
 from oslo_serialization import jsonutils
 from oslo_utils import uuidutils
 import testscenarios
@@ -389,6 +390,19 @@ class ExtGwModeIntTestCase(test_db_base_plugin_v2.NeutronDbPluginV2TestCase,
                             expected_code=expected_code,
                             neutron_context=neutron_context)
 
+    def test_router_gateway_set_retry(self):
+        with self.router() as r, self.subnet() as s:
+            ext_net_id = s['subnet']['network_id']
+            self._set_net_external(ext_net_id)
+            with mock.patch.object(
+                l3_db.L3_NAT_dbonly_mixin, '_validate_gw_info',
+                side_effect=[db_exc.RetryRequest(None), ext_net_id]):
+                    self._set_router_external_gateway(r['router']['id'],
+                                                      ext_net_id)
+            res = self._show('routers', r['router']['id'])['router']
+            self.assertEqual(ext_net_id,
+                             res['external_gateway_info']['network_id'])
+
     def test_router_create_with_gwinfo_invalid_ext_ip(self):
         with self.subnet() as s:
             self._set_net_external(s['subnet']['network_id'])