diff --git a/awx/main/models/notifications.py b/awx/main/models/notifications.py
index 11d97c7690..33562e7fca 100644
--- a/awx/main/models/notifications.py
+++ b/awx/main/models/notifications.py
@@ -12,7 +12,7 @@ from django.core.mail.message import EmailMessage
 from django.db import connection
 from django.utils.translation import ugettext_lazy as _
 from django.utils.encoding import smart_str, force_text
-from jinja2 import sandbox
+from jinja2 import sandbox, ChainableUndefined
 from jinja2.exceptions import TemplateSyntaxError, UndefinedError, SecurityError
 
 # AWX
@@ -429,7 +429,7 @@ class JobNotificationMixin(object):
         raise RuntimeError("Define me")
 
     def build_notification_message(self, nt, status):
-        env = sandbox.ImmutableSandboxedEnvironment()
+        env = sandbox.ImmutableSandboxedEnvironment(undefined=ChainableUndefined)
 
         from awx.api.serializers import UnifiedJobSerializer
         job_serialization = UnifiedJobSerializer(self).to_representation(self)
diff --git a/awx_collection/test/awx/test_notification_template.py b/awx_collection/test/awx/test_notification_template.py
index 28f7c4ecee..96fbd5e56c 100644
--- a/awx_collection/test/awx/test_notification_template.py
+++ b/awx_collection/test/awx/test_notification_template.py
@@ -3,7 +3,7 @@ __metaclass__ = type
 
 import pytest
 
-from awx.main.models import NotificationTemplate
+from awx.main.models import NotificationTemplate, Job
 
 
 def compare_with_encrypted(model_config, param_config):
@@ -109,3 +109,32 @@ def test_deprecated_to_modern_no_op(run_module, admin_user, organization):
     ), admin_user)
     assert not result.get('failed', False), result.get('msg', result)
     assert not result.pop('changed', None), result
+
+
+@pytest.mark.django_db
+def test_build_notification_message_undefined(run_module, admin_user, organization):
+    """Job notification templates may encounter undefined values in the context when they are
+    rendered. Make sure that accessing attributes or items of an undefined value returns another
+    instance of Undefined, rather than raising an UndefinedError. This enables the use of expressions
+    like "{{ job.created_by.first_name | default('unknown') }}"."""
+    job = Job.objects.create(name='foobar')
+
+    nt_config = {
+        'url': 'http://www.example.com/hook',
+        'headers': {
+            'X-Custom-Header': 'value123'
+        }
+    }
+    custom_start_template = {'body': '{"started_by": "{{ job.summary_fields.created_by.username | default(\'My Placeholder\') }}"}'}
+    messages = {'started': custom_start_template, 'success': None, 'error': None, 'workflow_approval': None}
+    result = run_module('tower_notification_template', dict(
+        name='foo-notification-template',
+        organization=organization.name,
+        notification_type='webhook',
+        notification_configuration=nt_config,
+        messages=messages,
+    ), admin_user)
+    nt = NotificationTemplate.objects.get(id=result['id'])
+
+    _, body = job.build_notification_message(nt, 'running')
+    assert '{"started_by": "My Placeholder"}' in body
diff --git a/requirements/requirements.in b/requirements/requirements.in
index cd06a749fb..f13ccb21b3 100644
--- a/requirements/requirements.in
+++ b/requirements/requirements.in
@@ -27,7 +27,7 @@ djangorestframework>=3.12.1
 djangorestframework-yaml
 GitPython>=3.1.1  # minimum to fix https://github.com/ansible/awx/issues/6119
 irc
-jinja2
+jinja2>=2.11.0  # required for ChainableUndefined
 jsonschema
 Markdown  # used for formatting API help
 openshift>=0.11.0  # minimum version to pull in new pyyaml for CVE-2017-18342