```
AttributeError: module 'posthog.queries.sessions' has no attribute 'Sessions'
(6 additional frame(s) were not displayed)
...
  File "posthog/api/dashboard.py", line 101, in get_items
    update_dashboard_items_cache(dashboard)
  File "posthog/tasks/update_cache.py", line 73, in update_dashboard_items_cache
    update_cache_item(cache_key, cache_type, payload)
  File "posthog/tasks/update_cache.py", line 64, in update_cache_item
    result = _calculate_by_filter(filter, key, team_id, cache_type)
  File "posthog/tasks/update_cache.py", line 144, in _calculate_by_filter
    insight_class = import_from(insight_class_path[0], insight_class_path[1])
  File "posthog/tasks/update_cache.py", line 132, in import_from
    return getattr(importlib.import_module(module), name)
```
posthog/settings.py
if url.endswith("/recorder.js"):
        headers["Cache-Control"] = "max-age=31536000, public"
WHITENOISE_ADD_HEADERS_FUNCTION = add_recorder_js_headers
if DEBUG and not TEST:
    print_warning(
        (
            "️Environment variable DEBUG is set - PostHog is running in DEVELOPMENT MODE!",
            "Be sure to unset DEBUG if this is supposed to be a PRODUCTION ENVIRONMENT!",
        )
    )
if not DEBUG and not TEST and SECRET_KEY == DEFAULT_SECRET_KEY:
    print_warning(
        (
            "You are using the default SECRET_KEY in a production environment!",
            "For the safety of your instance, you must generate and set a unique key.",
            "More information on https://posthog.com/docs/deployment/securing-posthog#secret-key",
        )
    )
    sys.exit("[ERROR] Default SECRET_KEY in production. Stopping Django server…\n")
def show_toolbar(request):