Django makemessages "struct.error: unpack requires a buffer of 4 bytes"

Question

I have a django instance packed in Docker container in docker-compose.

I'm trying to generate makemessages files for project, but when I try to run makemessages, that's what I receieve in response

root@6fc510c9c5d1:/code# python manage.py makemessages
/usr/local/lib/python3.6/dist-packages/daphne/server.py:12: UserWarning: Something has already installed a non-asyncio Twisted reactor. Attempting to uninstall it; you can fix this warning by importing daphne.server early in your codebase or finding the package that imports Twisted and importing it later on.
  UserWarning,
Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/__init__.py", line 347, in execute
    django.setup()
  File "/usr/local/lib/python3.6/dist-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/local/lib/python3.6/dist-packages/django/apps/registry.py", line 112, in populate
    app_config.import_models()
  File "/usr/local/lib/python3.6/dist-packages/django/apps/config.py", line 198, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/local/lib/python3.6/dist-packages/django/contrib/auth/models.py", line 94, in <module>
    class Group(models.Model):
  File "/usr/local/lib/python3.6/dist-packages/django/db/models/base.py", line 152, in __new__
    new_class.add_to_class(obj_name, obj)
  File "/usr/local/lib/python3.6/dist-packages/django/db/models/base.py", line 315, in add_to_class
    value.contribute_to_class(cls, name)
  File "/usr/local/lib/python3.6/dist-packages/django/db/models/fields/related.py", line 1586, in contribute_to_class
    self.remote_field.through = create_many_to_many_intermediary_model(self, cls)
  File "/usr/local/lib/python3.6/dist-packages/django/db/models/fields/related.py", line 1051, in create_many_to_many_intermediary_model
    'verbose_name': _('%(from)s-%(to)s relationship') % {'from': from_, 'to': to},
  File "/usr/local/lib/python3.6/dist-packages/django/utils/functional.py", line 148, in __mod__
    return str(self) % rhs
  File "/usr/local/lib/python3.6/dist-packages/django/utils/functional.py", line 112, in __text_cast
    return func(*self.__args, **self.__kw)
  File "/usr/local/lib/python3.6/dist-packages/django/utils/translation/__init__.py", line 77, in gettext
    return _trans.gettext(message)
  File "/usr/local/lib/python3.6/dist-packages/django/utils/translation/trans_real.py", line 312, in gettext
    _default = _default or translation(settings.LANGUAGE_CODE)
  File "/usr/local/lib/python3.6/dist-packages/django/utils/translation/trans_real.py", line 221, in translation
    _translations[language] = DjangoTranslation(language)
  File "/usr/local/lib/python3.6/dist-packages/django/utils/translation/trans_real.py", line 122, in __init__
    self._add_installed_apps_translations()
  File "/usr/local/lib/python3.6/dist-packages/django/utils/translation/trans_real.py", line 170, in _add_installed_apps_translations
    translation = self._new_gnu_trans(localedir)
  File "/usr/local/lib/python3.6/dist-packages/django/utils/translation/trans_real.py", line 149, in _new_gnu_trans
    fallback=use_null_fallback)
  File "/usr/lib/python3.6/gettext.py", line 538, in translation
    t = _translations.setdefault(key, class_(fp))
  File "/usr/lib/python3.6/gettext.py", line 254, in __init__
    self._parse(fp)
  File "/usr/lib/python3.6/gettext.py", line 345, in _parse
    magic = unpack('<I', buf[:4])[0]
struct.error: unpack requires a buffer of 4 bytes

Do you have any ideas what it can be?

Answer 1

It might be raised by your .mo file(s). Please check if this file is empty. If this is indeed the case. Remove your .mo file and rerun the makemessages command.

It should solve the issue you're having.

If this doesn't solve your issue. Try this:

1. Save all the .po files in a different location (create a backup of your locale file)
2. delete all the languages in locale folder.
3. Rerun the command

Answer 2

In my case the problem was because I had errors on the django-admin makemessages command. I had a msgstr "" missing and it was propted as a fatal error, once I added it the django.mo file got filled and everything worked fine.