'FieldInstanceTracker' object has no attribute 'saved_data'

Internal Server Error: /app/chronos/timetable/teacher/4957/

AttributeError at /app/chronos/timetable/teacher/4957/
'FieldInstanceTracker' object has no attribute 'saved_data'

Request Method: GET
Request URL: [1] https://info.katharineum.de/app/chronos/timetable/teacher/4957/
Django Version: 3.2.11
Python Executable: /usr/bin/uwsgi-core
Python Version: 3.9.2
Python Path: ['/srv/aleksis', '.', '', '/usr/lib/python39.zip', '/usr/lib/python3.9', '/usr/lib/python3.9/lib-dynload', '/srv/aleksis/envs/production/lib/python3.9/site-packages']
Server time: Tue, 01 Feb 2022 12:07:52 +0100
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.sites',
'django.contrib.staticfiles',
'django.contrib.humanize',
'django_uwsgi',
'django_extensions',
'guardian',
'rules.apps.AutodiscoverRulesConfig',
'haystack',
'polymorphic',
'dj_cleavejs.apps.DjCleaveJSConfig',
'dbbackup',
'django_celery_beat',
'django_celery_results',
'celery_progress',
'health_check.contrib.celery',
'djcelery_email',
'celery_haystack',
'sass_processor',
'django_any_js',
'django_yarnpkg',
'django_tables2',
'maintenance_mode',
'menu_generator',
'reversion',
'phonenumber_field',
'debug_toolbar',
'django_prometheus',
'django_select2',
'templated_email',
'html2text',
'django_otp.plugins.otp_totp',
'django_otp.plugins.otp_static',
'django_otp',
'otp_yubikey',
'aleksis.core',
'allauth',
'allauth.account',
'allauth.socialaccount',
'invitations',
'health_check',
'health_check.db',
'health_check.cache',
'health_check.storage',
'health_check.contrib.psutil',
'health_check.contrib.migrations',
'dynamic_preferences',
'dynamic_preferences.users.apps.UserPreferencesConfig',
'impersonate',
'two_factor',
'material',
'ckeditor',
'ckeditor_uploader',
'django_js_reverse',
'colorfield',
'django_bleach',
'favicon',
'django_filters',
'oauth2_provider',
'rest_framework',
'extra_views',
'feeds',
'aleksis.apps.untis.apps.UntisConfig',
'aleksis.apps.hjelp.apps.HjelpConfig',
'aleksis.apps.resint.apps.ResintConfig',
'aleksis.apps.abi.apps.DefaultConfig',
'aleksis.apps.alsijil.apps.AlsijilConfig',
'aleksis.apps.donations.apps.DonationsConfig',
'aleksis.apps.fritak.apps.FritakConfig',
'aleksis.apps.ldap.apps.LDAPConfig',
'aleksis.apps.csv_import.apps.CSVImportConfig',
'aleksis.apps.chronos.apps.ChronosConfig',
'aleksis.apps.order.apps.DefaultConfig',
'aleksis.apps.evalu.apps.DefaultConfig',
'aleksis.apps.dashboardfeeds.apps.DefaultConfig',
'cachalot',
'django_cleanup.apps.CleanupConfig']
Installed Middleware:
['django_prometheus.middleware.PrometheusBeforeMiddleware',
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'debug_toolbar.middleware.DebugToolbarMiddleware',
'django.middleware.locale.LocaleMiddleware',
'django.middleware.http.ConditionalGetMiddleware',
'django.contrib.sites.middleware.CurrentSiteMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django_otp.middleware.OTPMiddleware',
'impersonate.middleware.ImpersonateMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
'maintenance_mode.middleware.MaintenanceModeMiddleware',
'aleksis.core.util.middlewares.EnsurePersonMiddleware',
'django_prometheus.middleware.PrometheusAfterMiddleware']
>
Traceback (most recent call last):
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/core/handlers/exception.py", line 47, in inner
   response = get_response(request)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/core/handlers/base.py", line 181, in _get_response
   response = wrapped_callback(request, *callback_args, **callback_kwargs)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/sentry_sdk/integrations/django/views.py", line 67, in sentry_wrapped_callback
   return callback(request, *args, **kwargs)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/rules/contrib/views.py", line 231, in _wrapped_view
   return view_func(request, *args, **kwargs)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/aleksis/apps/chronos/views.py", line 144, in timetable
   timetable = build_timetable(type_, el, wanted_week, with_holidays=is_smart)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/aleksis/apps/chronos/util/build.py", line 225, in build_timetable
   for supervision in supervisions:
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/db/models/query.py", line 280, in __iter__
   self._fetch_all()
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/db/models/query.py", line 1324, in _fetch_all
   self._result_cache = list(self._iterable_class(self))
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/db/models/query.py", line 71, in __iter__
   rel_populator.populate(row, obj)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/db/models/query.py", line 2000, in populate
   obj = self.model_cls.from_db(self.db, self.init_list, obj_data)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/db/models/base.py", line 515, in from_db
   new = cls(*values)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/db/models/base.py", line 505, in __init__
   post_init.send(sender=cls, instance=self)
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/dispatch/dispatcher.py", line 180, in send
   return [
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/dispatch/dispatcher.py", line 181, in
   (receiver, receiver(signal=self, sender=sender, **named))
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/model_utils/tracker.py", line 231, in initialize_tracker
   tracker.set_saved_fields()
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/model_utils/tracker.py", line 106, in set_saved_fields
   self.saved_data = self.current()
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/model_utils/tracker.py", line 126, in current
   return {f: self.get_field_value(f) for f in fields}
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/model_utils/tracker.py", line 126, in
   return {f: self.get_field_value(f) for f in fields}
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/model_utils/tracker.py", line 100, in get_field_value
   return getattr(self.instance, self.field_map[field])
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/django/db/models/query_utils.py", line 144, in __get__
   instance.refresh_from_db(fields=[field_name])
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/model_utils/tracker.py", line 254, in inner
   getattr(instance, self.attname).set_saved_fields(
 File "/srv/aleksis/envs/production/lib/python3.9/site-packages/model_utils/tracker.py", line 108, in set_saved_fields
   self.saved_data.update(**self.current(fields=fields))

Exception Type: AttributeError at /app/chronos/timetable/teacher/4957/
Exception Value: 'FieldInstanceTracker' object has no attribute 'saved_data'
Request information:
USER: ***

GET: No GET data

POST: No POST data

FILES: No FILES data