diff --git a/konviva-events/app/app.py b/konviva-events/app/app.py
index 22f2902..04a4ce1 100644
--- a/konviva-events/app/app.py
+++ b/konviva-events/app/app.py
@@ -23,7 +23,7 @@ dyn = DynamoDBPersistenceLayer(ENROLLMENT_TABLE, dynamodb_client)
 
 @app.post('/')
 @tracer.capture_method
-def update_enrollment():
+def postback():
     json_body = app.current_event.json_body
 
     status = json_body['status']
diff --git a/konviva-events/app/enrollment.py b/konviva-events/app/enrollment.py
index bcdeb82..b701a49 100644
--- a/konviva-events/app/enrollment.py
+++ b/konviva-events/app/enrollment.py
@@ -65,6 +65,7 @@ def update_progress(
                     ':progress': progress,
                     ':updated_at': now_,
                 },
+                exc_cls=EnrollmentConflictError,
             )
             # Record the start date if it does not already exist
             transact.put(
@@ -140,7 +141,9 @@ def set_score(
                     user_id=user_id,
                     course_id=course_id,
                     cert_exp_interval=int(
-                        glom(enrollment, 'metadata__course.cert.exp_interval')
+                        glom(
+                            enrollment, 'metadata__course.cert.exp_interval', default=0
+                        )
                     ),
                     dedup_window_offset_days=int(
                         enrollment['dedup_window_offset_days']
@@ -216,39 +219,42 @@ def _set_status_as_completed(
             },
             cond_expr='attribute_not_exists(sk)',
         )
-        transact.put(
-            item={
-                'id': id,
-                'sk': 'SCHEDULE#REMINDER_CERT_EXPIRATION_BEFORE_30_DAYS',
-                'ttl': cert_expiration_reminder_ttl,
-                'created_at': now_,
-            }
-        )
-        transact.put(
-            item={
-                'id': id,
-                'sk': 'SCHEDULE#SET_AS_ARCHIVED',
-                'ttl': archive_ttl,
-                'created_at': now_,
-            }
-        )
-        transact.put(
-            item={
-                'id': id,
-                'sk': 'LOCK',
-                'ttl': deduplication_lock_ttl,
-                'created_at': now_,
-            }
-        )
-        transact.put(
-            item={
-                'id': 'LOCK',
-                'sk': lock_hash,
-                'enrollment_id': id,
-                'ttl': deduplication_lock_ttl,
-                'created_at': now_,
-            }
-        )
+
+        if cert_exp_interval:
+            transact.put(
+                item={
+                    'id': id,
+                    'sk': 'SCHEDULE#REMINDER_CERT_EXPIRATION_BEFORE_30_DAYS',
+                    'ttl': cert_expiration_reminder_ttl,
+                    'created_at': now_,
+                }
+            )
+            transact.put(
+                item={
+                    'id': id,
+                    'sk': 'SCHEDULE#SET_AS_ARCHIVED',
+                    'ttl': archive_ttl,
+                    'created_at': now_,
+                }
+            )
+            transact.put(
+                item={
+                    'id': id,
+                    'sk': 'LOCK',
+                    'ttl': deduplication_lock_ttl,
+                    'created_at': now_,
+                }
+            )
+            transact.put(
+                item={
+                    'id': 'LOCK',
+                    'sk': lock_hash,
+                    'enrollment_id': id,
+                    'ttl': deduplication_lock_ttl,
+                    'created_at': now_,
+                }
+            )
+
         # Remove reminders and policies that no longer apply
         transact.delete(
             key=KeyPair(
@@ -420,4 +426,6 @@ class EnrollmentNotFoundError(NotFoundError):
         super().__init__('Enrollment not found')
 
 
-class EnrollmentConflictError(BadRequestError): ...
+class EnrollmentConflictError(BadRequestError):
+    def __init__(self, *_):
+        super().__init__('Enrollment conflict')