fix: LastSeenCoursewareTimezone race condition

openedx/core/djangoapps/courseware_api/views.py

@@ -4,7 +4,7 @@
 from completion.exceptions import UnavailableCompletionData
 from completion.utilities import get_key_to_last_completed_block
 from django.conf import settings
-from django.db import transaction
+from django.db import transaction, IntegrityError
 from django.utils.decorators import method_decorator
 from django.utils.functional import cached_property
 from edx_django_utils.cache import TieredCache
@@ -498,12 +498,20 @@ def set_last_seen_courseware_timezone(self, user):
         browser_timezone = self.request.query_params.get('browser_timezone', None)
         cached_value = TieredCache.get_cached_response(cache_key)
         if not cached_value.is_found:
-            if browser_timezone:
-                TieredCache.set_all_tiers(cache_key, str(browser_timezone), 86400)  # Refresh the cache daily
+            return
+
+        if browser_timezone:
+            TieredCache.set_all_tiers(cache_key, str(browser_timezone), 86400)  # Refresh the cache daily
+            try:
                 LastSeenCoursewareTimezone.objects.update_or_create(
                     user=user,
                     defaults={'last_seen_courseware_timezone': browser_timezone},
                 )
+            except IntegrityError:
+                # Race condition: record already exists, just update it
+                obj = LastSeenCoursewareTimezone.objects.get(user=user)
+                obj.last_seen_courseware_timezone = browser_timezone
+                obj.save()
 
     def get_object(self):
         """