diff --git a/cms/djangoapps/contentstore/rest_api/v1/views/tests/test_proctoring.py b/cms/djangoapps/contentstore/rest_api/v1/views/tests/test_proctoring.py
index 66b5f46128..8e220a334c 100644
--- a/cms/djangoapps/contentstore/rest_api/v1/views/tests/test_proctoring.py
+++ b/cms/djangoapps/contentstore/rest_api/v1/views/tests/test_proctoring.py
@@ -277,18 +277,14 @@ class ProctoringExamSettingsPostTests(
 
         # response is correct
         assert response.status_code == status.HTTP_400_BAD_REQUEST
-        self.assertDictEqual(
-            response.data,
+        self.assertIn(
             {
-                "detail": [
-                    {
-                        "proctoring_provider": (
-                            "The selected proctoring provider, notvalidprovider, is not a valid provider. "
-                            "Please select from one of ['test_proctoring_provider']."
-                        )
-                    }
-                ]
+                "proctoring_provider": (
+                    "The selected proctoring provider, notvalidprovider, is not a valid provider. "
+                    "Please select from one of ['test_proctoring_provider']."
+                )
             },
+            response.data['detail'],
         )
 
         # course settings have been updated
@@ -408,18 +404,14 @@ class ProctoringExamSettingsPostTests(
 
         # response is correct
         assert response.status_code == status.HTTP_400_BAD_REQUEST
-        self.assertDictEqual(
-            response.data,
+        self.assertIn(
             {
-                "detail": [
-                    {
-                        "proctoring_provider": (
-                            "The selected proctoring provider, lti_external, is not a valid provider. "
-                            "Please select from one of ['null']."
-                        )
-                    }
-                ]
+                "proctoring_provider": (
+                    "The selected proctoring provider, lti_external, is not a valid provider. "
+                    "Please select from one of ['null']."
+                )
             },
+            response.data['detail'],
         )
 
         # course settings have been updated
diff --git a/cms/djangoapps/contentstore/views/tests/test_exam_settings_view.py b/cms/djangoapps/contentstore/views/tests/test_exam_settings_view.py
index a7ee7f0ab0..0f38722e12 100644
--- a/cms/djangoapps/contentstore/views/tests/test_exam_settings_view.py
+++ b/cms/djangoapps/contentstore/views/tests/test_exam_settings_view.py
@@ -162,6 +162,39 @@ class TestExamSettingsView(CourseTestCase, UrlResetMixin):
         else:
             assert 'To update these settings go to the Advanced Settings page.' in alert_text
 
+    @override_settings(
+        PROCTORING_BACKENDS={
+            'DEFAULT': 'test_proctoring_provider',
+            'proctortrack': {},
+            'test_proctoring_provider': {},
+        },
+        FEATURES=FEATURES_WITH_EXAM_SETTINGS_ENABLED,
+    )
+    @ddt.data(
+        "advanced_settings_handler",
+        "course_handler",
+    )
+    def test_invalid_provider_alert(self, page_handler):
+        """
+        An alert should appear if the course has a proctoring provider that is not valid.
+        """
+        # create an error by setting an invalid proctoring provider
+        self.course.proctoring_provider = 'invalid_provider'
+        self.course.enable_proctored_exams = True
+        self.save_course()
+
+        url = reverse_course_url(page_handler, self.course.id)
+        resp = self.client.get(url, HTTP_ACCEPT='text/html')
+        alert_text = self._get_exam_settings_alert_text(resp.content)
+        assert (
+            'This course has proctored exam settings that are incomplete or invalid.'
+            in alert_text
+        )
+        assert (
+            'The proctoring provider configured for this course, \'invalid_provider\', is not valid.'
+            in alert_text
+        )
+
     @ddt.data(
         "advanced_settings_handler",
         "course_handler",
diff --git a/cms/djangoapps/models/settings/course_metadata.py b/cms/djangoapps/models/settings/course_metadata.py
index 07ee360ed7..5d4ac5a4a3 100644
--- a/cms/djangoapps/models/settings/course_metadata.py
+++ b/cms/djangoapps/models/settings/course_metadata.py
@@ -490,6 +490,24 @@ class CourseMetadata:
             enable_proctoring = block.enable_proctored_exams
 
         if enable_proctoring:
+
+            if proctoring_provider_model:
+                proctoring_provider = proctoring_provider_model.get('value')
+            else:
+                proctoring_provider = block.proctoring_provider
+
+            # If the proctoring provider stored in the course block no longer
+            # matches the available providers for this instance, show an error
+            if proctoring_provider not in available_providers:
+                message = (
+                    f'The proctoring provider configured for this course, \'{proctoring_provider}\', is not valid.'
+                )
+                errors.append({
+                    'key': 'proctoring_provider',
+                    'message': message,
+                    'model': proctoring_provider_model
+                })
+
             # Require a valid escalation email if Proctortrack is chosen as the proctoring provider
             escalation_email_model = settings_dict.get('proctoring_escalation_email')
             if escalation_email_model:
@@ -497,11 +515,6 @@ class CourseMetadata:
             else:
                 escalation_email = block.proctoring_escalation_email
 
-            if proctoring_provider_model:
-                proctoring_provider = proctoring_provider_model.get('value')
-            else:
-                proctoring_provider = block.proctoring_provider
-
             missing_escalation_email_msg = 'Provider \'{provider}\' requires an exam escalation contact.'
             if proctoring_provider_model and proctoring_provider == 'proctortrack':
                 if not escalation_email: