Удаление пользователей django 3

Пытаюсь удалить пользователя через админку django 3.1, но поучаю ошибку:

__str__ returned non-string (type User)

Полный код ошибки:

Traceback (most recent call last):
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/core/handlers/base.py", line 179, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 614, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/utils/decorators.py", line 130, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/views/decorators/cache.py", line 44, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/contrib/admin/sites.py", line 233, in inner
    return view(request, *args, **kwargs)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/utils/decorators.py", line 43, in _wrapper
    return bound_method(*args, **kwargs)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/utils/decorators.py", line 130, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 1719, in changelist_view
    response = self.response_action(request, queryset=cl.get_queryset(request))
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 1402, in response_action
    response = func(self, request, queryset)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/contrib/admin/actions.py", line 28, in delete_selected
    deletable_objects, model_count, perms_needed, protected = modeladmin.get_deleted_objects(queryset, request)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 1841, in get_deleted_objects
    return get_deleted_objects(objs, request, self.admin_site)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-packages/django/contrib/admin/utils.py", line 151, in get_deleted_objects
    to_delete = collector.nested(format_callback)
  File "/home/coder8080/Документы/disk/venv/lib/python3.8/site-

В приндипе понял, что ошибка где-то в модельках User в функции str. Если нет другого решения, то где хранится этот код, чтобы переписать функцию str?

пробовал collectstatic, makemigrations && migrate, не помогло.