Import errors in settings cause confusing error messages

[Sasha Romijn]

When the settings file itself has an import error, the error message suggests that the settings file could not be found. This can be very confusing, especially for new users.

Currently, the traceback is:

Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/erik/dev/django/django/core/management/__init__.py", line 399, in execute_from_command_line
    utility.execute()
  File "/Users/erik/dev/django/django/core/management/__init__.py", line 392, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/erik/dev/django/django/core/management/__init__.py", line 263, in fetch_command
    app_name = get_commands()[subcommand]
  File "/Users/erik/dev/django/django/core/management/__init__.py", line 109, in get_commands
    apps = settings.INSTALLED_APPS
  File "/Users/erik/dev/django/django/conf/__init__.py", line 54, in __getattr__
    self._setup(name)
  File "/Users/erik/dev/django/django/conf/__init__.py", line 49, in _setup
    self._wrapped = Settings(settings_module)
  File "/Users/erik/dev/django/django/conf/__init__.py", line 130, in __init__
    raise ImportError("Could not import settings '%s' (Is it on sys.path?): %s" % (self.SETTINGS_MODULE, e))
ImportError: Could not import settings 'django5622.settings' (Is it on sys.path?): No module named foo

Whereas in reality the settings file was found, but contained an error.

Adding a bit of info on the original traceback makes this very obvious:

Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/erik/dev/django/django/core/management/__init__.py", line 399, in execute_from_command_line
    utility.execute()
  File "/Users/erik/dev/django/django/core/management/__init__.py", line 392, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/erik/dev/django/django/core/management/__init__.py", line 263, in fetch_command
    app_name = get_commands()[subcommand]
  File "/Users/erik/dev/django/django/core/management/__init__.py", line 109, in get_commands
    apps = settings.INSTALLED_APPS
  File "/Users/erik/dev/django/django/conf/__init__.py", line 55, in __getattr__
    self._setup(name)
  File "/Users/erik/dev/django/django/conf/__init__.py", line 50, in _setup
    self._wrapped = Settings(settings_module)
  File "/Users/erik/dev/django/django/conf/__init__.py", line 135, in __init__
    raise ImportError(msg)
ImportError: Could not import settings 'django5622.settings' (Is it on sys.path?): No module named o in /Users/erik/dev/django5622/django5622/settings.py:12

[Sasha Romijn]

Pull request with patch in ​https://github.com/django/django/pull/1112

[svisser]

The error message now kinda assumes the settings module can be found. If not, it'll appear that an error occurred "somewhere in Django":

ImportError: Could not import settings 'djangoproject.settings' (Is it on sys.path?): No module named settings in /Users/simeon/django/django/utils/importlib.py:35

[Anssi Kääriäinen]

Maybe the error message could point out that one possible cause is import error in settings file itself?

[Sasha Romijn]

@akaariai: yes, that's actually a more sensible and simpler solution. It also fixes svisser's concern. I built the original patch on the assumption that there were more types of errors that caused confusing messages, but it seems to be limited to import errors.

New trivial PR in ​https://github.com/django/django/pull/1217, tests run.

[Chris Wilson]

Looks good to me.

[Erik Romijn <erik@…>]

In 9a524e3c5bd8fafd4996a6f1486de8a2cbb052a2:

Fixed #20443 -- Import errors in settings cause confusing error messages

[Claude Paroz <claude@…>]

In 1a4b43521883ce85dfbda29b89822a59ffc5220b:

Merge pull request #1217 from erikr/better-settings-errors2

Fixed #20443 -- Import errors in settings cause confusing error messages