diff --git a/awx/api/generics.py b/awx/api/generics.py
index e17d8b7a06..0f29ef7ca1 100644
--- a/awx/api/generics.py
+++ b/awx/api/generics.py
@@ -227,7 +227,10 @@ class APIView(views.APIView):
             if type(response.data) is dict:
                 msg_data['error'] = response.data.get('error', response.status_text)
             elif type(response.data) is list:
-                msg_data['error'] = ", ".join(list(map(lambda x: x.get('error', response.status_text), response.data)))
+                if len(response.data) > 0 and isinstance(response.data[0], str):
+                    msg_data['error'] = str(response.data[0])
+                else:
+                    msg_data['error'] = ", ".join(list(map(lambda x: x.get('error', response.status_text), response.data)))
             else:
                 msg_data['error'] = response.status_text
 
diff --git a/awx/main/tests/functional/dab_rbac/test_dab_rbac_api.py b/awx/main/tests/functional/dab_rbac/test_dab_rbac_api.py
index 66df98b07a..4d2f91129e 100644
--- a/awx/main/tests/functional/dab_rbac/test_dab_rbac_api.py
+++ b/awx/main/tests/functional/dab_rbac/test_dab_rbac_api.py
@@ -2,6 +2,7 @@ import pytest
 
 from django.contrib.contenttypes.models import ContentType
 from django.urls import reverse as django_reverse
+from django.test.utils import override_settings
 
 from awx.api.versioning import reverse
 from awx.main.models import JobTemplate, Inventory, Organization
@@ -118,3 +119,12 @@ def test_workflow_creation_permissions(setup_managed_roles, organization, workfl
     org_wf_rd.give_permission(rando, organization)
 
     assert access.can_add({'name': 'foo-flow', 'organization': organization.pk})
+
+
+@pytest.mark.django_db
+@override_settings(ALLOW_LOCAL_RESOURCE_MANAGEMENT=False)
+def test_team_member_role_not_assignable(team, rando, post, admin_user, setup_managed_roles):
+    member_rd = RoleDefinition.objects.get(name='Organization Member')
+    url = django_reverse('roleuserassignment-list')
+    r = post(url, data={'object_id': team.id, 'role_definition': member_rd.id, 'user': rando.id}, user=admin_user, expect=400)
+    assert 'Not managed locally' in str(r.data)