No module named constants error - html

Question

I have a project in progress. In this project I have to change some reports that they implement by XML code.
When I run my project with "python manage.py runserver"it runs truthfully and I can change my XML code and see the HTML files on chrome but when I want to see the PDF file of reports I get an error that says:
>"IndexError, your list is out of range"
so I start to debug it, in this process debugger said
"from django.db.models.constants import LOOKUP_SEP No module named constants".
this is whole trace back:
>Unhandled exception in thread started by <_pydev_bundle.pydev_monkey._NewThreadStartupWithTrace instance at 0x7f45ea1f3b48>
Traceback (most recent call last):
File "/home/rajabi/pycharm-community-2017.1.4/helpers/pydev/_pydev_bundle/pydev_monkey.py", line 589, in __call__
return self.original_func(*self.args, **self.kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/runserver.py", line 91, in inner_run
self.validate(display_num_errors=True)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 266, in validate
num_errors = get_validation_errors(s, app)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/validation.py", line 30, in get_validation_errors
for (app_name, error) in get_app_errors().items():
File "/usr/local/lib/python2.7/dist-packages/django/db/models/loading.py", line 158, in get_app_errors
self._populate()
File "/usr/local/lib/python2.7/dist-packages/django/db/models/loading.py", line 67, in _populate
self.load_app(app_name)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/loading.py", line 88, in load_app
models = import_module('.models', app_name)
File "/usr/local/lib/python2.7/dist-packages/django/utils/importlib.py", line 35, in import_module
__import__(name)
File "/home/rajabi/Desktop/tina/clone-2017-07-05/rtis/src/saed/activities/models.py", line 7, in <module>
from saed.activities.base import models
File "/home/rajabi/Desktop/tina/clone-2017-07-05/rtis/src/saed/activities/base/models.py", line 16, in <module>
from model_utils.managers import InheritanceManager
File "/usr/local/lib/python2.7/dist-packages/model_utils/managers.py", line 13, in <module>
from django.db.models.constants import LOOKUP_SEP
ImportError: No module named constants
what should I do?
django==1.4
python==2.7.12
tastypie == 0.9.16
I can't change my django and python version.

Answer 1

This part of the traceback is showing you that the error is coming from django-model-utils.
File "/usr/local/lib/python2.7/dist-packages/model_utils/managers.py", line 13, in <module>
from django.db.models.constants import LOOKUP_SEP
The release notes say that support for Django 1.4 was dropped in version 3.0.
You could try installing an early version of django-model-utils, but really you should upgrade Django. Django 1.4 is years out of date and insecure.