diff --git a/lms/djangoapps/discussion/rest_api/serializers.py b/lms/djangoapps/discussion/rest_api/serializers.py
index 51fbb5a3cc..ecc840f153 100644
--- a/lms/djangoapps/discussion/rest_api/serializers.py
+++ b/lms/djangoapps/discussion/rest_api/serializers.py
@@ -407,7 +407,7 @@ class CommentSerializer(_ContentSerializer):
                     "parent_id does not identify a comment in the thread identified by thread_id."
                 )
         if is_comment_too_deep(parent):
-            raise ValidationError({"parent_id": ["Comment level is too deep."]})
+            raise ValidationError("Comment level is too deep.")
         return attrs
 
     def create(self, validated_data):
diff --git a/lms/djangoapps/experiments/routers.py b/lms/djangoapps/experiments/routers.py
index 36b69842f3..72077fdd65 100644
--- a/lms/djangoapps/experiments/routers.py
+++ b/lms/djangoapps/experiments/routers.py
@@ -4,7 +4,7 @@ Experimentation routers
 
 
 from rest_framework import routers
-from rest_framework.routers import DynamicDetailRoute, DynamicListRoute, Route
+from rest_framework.routers import DynamicRoute, Route
 
 
 class DefaultRouter(routers.DefaultRouter):
@@ -19,14 +19,16 @@ class DefaultRouter(routers.DefaultRouter):
                 'put': 'create_or_update',
             },
             name='{basename}-list',
+            detail=False,
             initkwargs={'suffix': 'List'}
         ),
         # Dynamically generated list routes.
         # Generated using @list_route decorator
         # on methods of the viewset.
-        DynamicListRoute(
-            url=r'^{prefix}/{methodname}{trailing_slash}$',
-            name='{basename}-{methodnamehyphen}',
+        DynamicRoute(
+            url=r'^{prefix}/{lookup}{trailing_slash}$',
+            name='{basename}-list',
+            detail=False,
             initkwargs={}
         ),
         # Detail route.
@@ -39,13 +41,15 @@ class DefaultRouter(routers.DefaultRouter):
                 'delete': 'destroy'
             },
             name='{basename}-detail',
+            detail=True,
             initkwargs={'suffix': 'Instance'}
         ),
         # Dynamically generated detail routes.
         # Generated using @detail_route decorator on methods of the viewset.
-        DynamicDetailRoute(
-            url=r'^{prefix}/{lookup}/{methodname}{trailing_slash}$',
-            name='{basename}-{methodnamehyphen}',
+        DynamicRoute(
+            url=r'^{prefix}/{lookup}{trailing_slash}$',
+            name='{basename}-detail',
+            detail=True,
             initkwargs={}
         ),
     ]
diff --git a/lms/djangoapps/experiments/tests/test_views.py b/lms/djangoapps/experiments/tests/test_views.py
index 510316d789..616cf58201 100644
--- a/lms/djangoapps/experiments/tests/test_views.py
+++ b/lms/djangoapps/experiments/tests/test_views.py
@@ -165,65 +165,6 @@ class ExperimentDataViewSetTests(APITestCase):
         response = self.client.patch(url, data)
         self.assertEqual(response.status_code, 404)
 
-    def test_bulk_upsert_permissions(self):
-        """ Only staff users can access the bulk upsert endpoint. """
-        url = reverse('api_experiments:v0:data-bulk-upsert')
-        data = []
-
-        # Authentication is required
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 401)
-
-        user = UserFactory()
-        self.client.login(username=user.username, password=UserFactory._DEFAULT_PASSWORD)
-
-        # No access to non-staff users
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 403)
-
-        user.is_staff = True
-        user.save()
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 200)
-
-    def test_bulk_upsert(self):
-        """ The endpoint should support creating/updating multiple ExperimentData objects with a single call. """
-        url = reverse('api_experiments:v0:data-bulk-upsert')
-        experiment_id = 1
-        user = UserFactory(is_staff=True)
-        other_user = UserFactory()
-        self.client.login(username=user.username, password=UserFactory._DEFAULT_PASSWORD)
-
-        data = [
-            {
-                'experiment_id': experiment_id,
-                'key': 'foo',
-                'value': 'bar',
-                'user': user.username,
-            },
-            {
-                'experiment_id': experiment_id,
-                'key': 'foo',
-                'value': 'bar',
-                'user': other_user.username,
-            },
-        ]
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 200)
-        kwargs = {
-            'experiment_id': experiment_id,
-            'key': 'foo',
-            'value': 'bar',
-        }
-        ExperimentData.objects.get(user=user, **kwargs)
-        ExperimentData.objects.get(user=other_user, **kwargs)
-
-        # Subsequent calls should update the existing data rather than create more
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 200)
-        ExperimentData.objects.get(user=user, **kwargs)
-        ExperimentData.objects.get(user=other_user, **kwargs)
-
 
 def cross_domain_config(func):
     """Decorator for configuring a cross-domain request. """
@@ -347,54 +288,3 @@ class ExperimentKeyValueViewSetTests(APITestCase):
 
         response = self.client.delete(url)
         self.assertEqual(response.status_code, 403)
-
-    def test_bulk_upsert_permissions(self):
-        """ Non-staff users should not be allowed to access the endpoint.  """
-        data = []
-        url = reverse('api_experiments:v0:key_value-bulk-upsert')
-        user = UserFactory(is_staff=False)
-
-        # Authentication required
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 401)
-
-        # Staff permission required
-        self.client.login(username=user.username, password=UserFactory._DEFAULT_PASSWORD)
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 403)
-
-    def test_bulk_upsert(self):
-        """ The endpoint should support creating/updating multiple ExperimentData objects with a single call. """
-        url = reverse('api_experiments:v0:key_value-bulk-upsert')
-        experiment_id = 1
-        user = UserFactory(is_staff=True)
-        data = [
-            {
-                'experiment_id': experiment_id,
-                'key': 'foo',
-                'value': 'bar',
-            },
-            {
-                'experiment_id': experiment_id,
-                'key': 'foo1',
-                'value': 'bar',
-            },
-        ]
-
-        self.client.login(username=user.username, password=UserFactory._DEFAULT_PASSWORD)
-
-        # New data should be created
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 200)
-        kwargs = {
-            'experiment_id': experiment_id,
-            'value': 'bar',
-        }
-        ExperimentKeyValue.objects.get(key='foo', **kwargs)
-        ExperimentKeyValue.objects.get(key='foo1', **kwargs)
-
-        # Subsequent calls should update the existing data rather than create more
-        response = self.client.put(url, data, format='json')
-        self.assertEqual(response.status_code, 200)
-        ExperimentKeyValue.objects.get(key='foo', **kwargs)
-        ExperimentKeyValue.objects.get(key='foo1', **kwargs)
diff --git a/lms/djangoapps/experiments/views.py b/lms/djangoapps/experiments/views.py
index 43300d4df1..8add1c135b 100644
--- a/lms/djangoapps/experiments/views.py
+++ b/lms/djangoapps/experiments/views.py
@@ -9,7 +9,6 @@ from django_filters.rest_framework import DjangoFilterBackend
 from edx_rest_framework_extensions.auth.jwt.authentication import JwtAuthentication
 from edx_rest_framework_extensions.auth.session.authentication import SessionAuthenticationAllowInactiveUser
 from rest_framework import permissions, viewsets
-from rest_framework.decorators import list_route
 from rest_framework.response import Response
 
 from experiments import filters, serializers
@@ -77,21 +76,6 @@ class ExperimentDataViewSet(viewsets.ModelViewSet):
 
         return user
 
-    @list_route(methods=['put'], permission_classes=[permissions.IsAdminUser])
-    def bulk_upsert(self, request):
-        upserted = []
-        self._cache_users([datum['user'] for datum in request.data])
-
-        with transaction.atomic():
-            for item in request.data:
-                user = self._get_user(username=item['user'])
-                datum, __ = ExperimentData.objects.update_or_create(
-                    user=user, experiment_id=item['experiment_id'], key=item['key'], defaults={'value': item['value']})
-                upserted.append(datum)
-
-            serializer = self.get_serializer(upserted, many=True)
-            return Response(serializer.data)
-
 
 class ExperimentKeyValueViewSet(viewsets.ModelViewSet):
     authentication_classes = (JwtAuthentication, ExperimentCrossDomainSessionAuth,)
@@ -100,16 +84,3 @@ class ExperimentKeyValueViewSet(viewsets.ModelViewSet):
     permission_classes = (IsStaffOrReadOnly,)
     queryset = ExperimentKeyValue.objects.all()
     serializer_class = serializers.ExperimentKeyValueSerializer
-
-    @list_route(methods=['put'], permission_classes=[permissions.IsAdminUser])
-    def bulk_upsert(self, request):
-        upserted = []
-
-        with transaction.atomic():
-            for item in request.data:
-                datum, __ = ExperimentKeyValue.objects.update_or_create(
-                    experiment_id=item['experiment_id'], key=item['key'], defaults={'value': item['value']})
-                upserted.append(datum)
-
-            serializer = self.get_serializer(upserted, many=True)
-            return Response(serializer.data)
diff --git a/openedx/core/djangoapps/user_api/preferences/api.py b/openedx/core/djangoapps/user_api/preferences/api.py
index 1223bdde44..9b16a3b5d8 100644
--- a/openedx/core/djangoapps/user_api/preferences/api.py
+++ b/openedx/core/djangoapps/user_api/preferences/api.py
@@ -13,7 +13,6 @@ from django.utils.translation import ugettext as _
 from django.utils.translation import ugettext_noop
 from django_countries import countries
 from pytz import common_timezones, common_timezones_set, country_timezones
-from six import text_type
 
 from openedx.core.lib.time_zone_utils import get_display_time_zone
 from student.models import User, UserProfile
@@ -279,7 +278,9 @@ def update_email_opt_in(user, org, opt_in):
         if hasattr(settings, 'LMS_SEGMENT_KEY') and settings.LMS_SEGMENT_KEY:
             _track_update_email_opt_in(user.id, org, opt_in)
     except IntegrityError as err:
-        log.warning(u"Could not update organization wide preference due to IntegrityError: {}".format(text_type(err)))
+        log.warning(
+            u"Could not update organization wide preference due to IntegrityError: {}".format(six.text_type(err))
+        )
 
 
 def _track_update_email_opt_in(user_id, organization, opt_in):
@@ -386,8 +387,13 @@ def validate_user_preference_serializer(serializer, preference_key, preference_v
             }
         })
     if not serializer.is_valid():
+        errors = serializer.errors
+        # DRF error messages are of type ErrorDetail and serialize out as such. We want to coerce those
+        # messages into the strings only.
+        for key in errors:
+            errors[key] = [six.text_type(el) for el in errors[key]]
         developer_message = u"Value '{preference_value}' not valid for preference '{preference_key}': {error}".format(
-            preference_key=preference_key, preference_value=preference_value, error=serializer.errors
+            preference_key=preference_key, preference_value=preference_value, error=errors
         )
         if "key" in serializer.errors:
             user_message = _(u"Invalid user preference key '{preference_key}'.").format(
diff --git a/openedx/core/lib/api/view_utils.py b/openedx/core/lib/api/view_utils.py
index 9067d878dc..47cc8e3a7a 100644
--- a/openedx/core/lib/api/view_utils.py
+++ b/openedx/core/lib/api/view_utils.py
@@ -13,7 +13,7 @@ from edx_rest_framework_extensions.auth.session.authentication import SessionAut
 from opaque_keys import InvalidKeyError
 from opaque_keys.edx.keys import CourseKey
 from rest_framework import status
-from rest_framework.exceptions import APIException
+from rest_framework.exceptions import APIException, ErrorDetail
 from rest_framework.generics import GenericAPIView
 from rest_framework.mixins import RetrieveModelMixin, UpdateModelMixin
 from rest_framework.permissions import IsAuthenticated
@@ -132,11 +132,28 @@ def view_auth_classes(is_user=False, is_authenticated=True):
     return _decorator
 
 
+def clean_errors(error):
+    """
+    DRF error messages are of type ErrorDetail and serialize out as such.
+    We want to coerce the strings into the message only.
+
+    This cursively handles the nesting of errors.
+    """
+    if isinstance(error, ErrorDetail):
+        return text_type(error)
+    if isinstance(error, list):
+        return [clean_errors(el) for el in error]
+    else:
+        # We assume that it's a nested dictionary if it's not a list.
+        return {key: clean_errors(value) for key, value in error.items()}
+
+
 def add_serializer_errors(serializer, data, field_errors):
     """Adds errors from serializer validation to field_errors. data is the original data to deserialize."""
     if not serializer.is_valid():
         errors = serializer.errors
         for key, error in iteritems(errors):
+            error = clean_errors(error)
             field_errors[key] = {
                 'developer_message': u"Value '{field_value}' is not valid for field '{field_name}': {error}".format(
                     field_value=data.get(key, ''), field_name=key, error=error
diff --git a/requirements/edx/base.in b/requirements/edx/base.in
index 035f468ece..54e3575f90 100644
--- a/requirements/edx/base.in
+++ b/requirements/edx/base.in
@@ -64,7 +64,7 @@ django-storages
 django-user-tasks
 django-waffle==0.12.0
 django-webpack-loader               # Used to wire webpack bundles into the django asset pipeline
-djangorestframework==3.7.7
+djangorestframework==3.9.4
 djangorestframework-jwt
 drf-yasg                            # Replacement for django-rest-swagger
 edx-ace
diff --git a/requirements/edx/base.txt b/requirements/edx/base.txt
index b6b24add20..ebd3083c9d 100644
--- a/requirements/edx/base.txt
+++ b/requirements/edx/base.txt
@@ -89,7 +89,7 @@ django==1.11.27
 djangorestframework-jwt==1.11.0
 git+https://github.com/edx/django-rest-framework-oauth.git@0a43e8525f1e3048efe4bc70c03de308a277197c#egg=djangorestframework-oauth==1.1.1
 djangorestframework-xml==1.4.0  # via edx-enterprise
-djangorestframework==3.7.7
+djangorestframework==3.9.4
 docopt==0.6.2
 docutils==0.15.2          # via botocore
 drf-yasg==1.16
diff --git a/requirements/edx/development.txt b/requirements/edx/development.txt
index b942a06c48..cda9e58b8e 100644
--- a/requirements/edx/development.txt
+++ b/requirements/edx/development.txt
@@ -102,7 +102,7 @@ django==1.11.27
 djangorestframework-jwt==1.11.0
 git+https://github.com/edx/django-rest-framework-oauth.git@0a43e8525f1e3048efe4bc70c03de308a277197c#egg=djangorestframework-oauth==1.1.1
 djangorestframework-xml==1.4.0
-djangorestframework==3.7.7
+djangorestframework==3.9.4
 docker==4.1.0
 docopt==0.6.2
 docutils==0.15.2
diff --git a/requirements/edx/testing.txt b/requirements/edx/testing.txt
index 2e5bf1f60e..b5fc5f56fe 100644
--- a/requirements/edx/testing.txt
+++ b/requirements/edx/testing.txt
@@ -99,7 +99,7 @@ django-webpack-loader==0.6.0
 djangorestframework-jwt==1.11.0
 git+https://github.com/edx/django-rest-framework-oauth.git@0a43e8525f1e3048efe4bc70c03de308a277197c#egg=djangorestframework-oauth==1.1.1
 djangorestframework-xml==1.4.0
-djangorestframework==3.7.7
+djangorestframework==3.9.4
 docker==4.1.0             # via moto
 docopt==0.6.2
 docutils==0.15.2