Docker Community Forums

Share and learn in the Docker community.

ModuleNotFoundError: No module named 'pytz'

I am trying to test my Django web app project using Docker. I run docker build -t backend:latest --build-arg FRONTEND_URL=localhost:3000 --build-arg BACKEND_URL=localhost:8000 . in powershell first. Then I run docker run -e "PORT=8000" -p 8000:8000 backend
It gives me the error

Watching for file changes with StatReloader
Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/", line 973, in _bootstrap_inner
  File "/usr/local/lib/python3.9/", line 910, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/utils/", line 64, in wrapper
    fn(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/core/management/commands/", line 115, in inner_run
  File "/usr/local/lib/python3.9/site-packages/django/utils/", line 87, in raise_last_exception
    raise _exception[1]
  File "/usr/local/lib/python3.9/site-packages/django/core/management/", line 381, in execute
  File "/usr/local/lib/python3.9/site-packages/django/utils/", line 64, in wrapper
    fn(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/", line 24, in setup
  File "/usr/local/lib/python3.9/site-packages/django/apps/", line 114, in populate
  File "/usr/local/lib/python3.9/site-packages/django/apps/", line 300, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/local/lib/python3.9/importlib/", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/src/meetings/", line 5, in <module>
    from pytz import timezone
ModuleNotFoundError: No module named 'pytz'

But I have pytz installed using pip install pytz so I don’t knwo what happened.

Without being a python developer I would say that django is what cannot find that module. Since I don’t know what is inside the Dockerfile I don’t know what could cause it. Can you share at least a part of your Dockerfile? The part where you install the module and maybe django. Of course the best would be to see the whole file but I don’t want to ask that if it is a private project. However I don’t think we can tell what the problem is without further details. Maybe python developers who use django could guess it based on their experience.

1 Like

I ran into this error as well, and noticed what @rimelek said about Django not being able to find pytz, so I added this line to my requirements.txt file which fixed this issue for me:
Seeing how Django 4 just came out, that might be related, but this combination of requirements seems to work for me: