[Fixed]-How to make Django's "DATETIME_FORMAT" active?

With:

USE_L10N = False

DATE_TIME takes effect, since the localization of l10n overrides DATETIME_FORMAT and DATE_FORMAT as documented at: https://docs.djangoproject.com/en/1.9/ref/settings/#date-format

As Ciro Santilli told, localization format overrides DATETIME_FORMAT in settings when USE_L10N = True. But you can still override DATETIME_FORMAT and other date/time formats by creating custom format files as described in Django documentation.

See detailed answer here.

You can override DATE_FORMAT, DATETIME_FORMAT, TIME_FORMAT and other date/time formats when USE_L10N = True by creating custom format files as described in Django documentation.

In summary:

1. Set FORMAT_MODULE_PATH = 'yourproject.formats' in settings.py
2. Create directory structure yourproject/formats/en (replacing en with the corresponding ISO 639-1 locale code if you are using other locale than English) and add __init__.py files to all directories to make it a valid Python module
3. Add formats.py to the leaf directory, containing the format definitions you want to override, e.g. DATE_FORMAT = 'j. F Y'.

Example from an actual project here.

The two setting directives should be defined in settings.py. Could you ensure that the same settings.py that you are editing is being read when you start the development server?

You could always drop to the Python interactive shell by running python manage.py shell, and run these commands to ensure whether the date/time format values are getting through fine:

from django.conf import settings
settings.DATE_FORMAT
settings.DATETIME_FORMAT

Ok, I forgot to look it up, but ticket #2203 deals with this. Unfortunately, the ticket remains in pending state.

I remember that for a project that used a certain trunk revision of the 0.97 branch of Django, I worked around that by overwriting the date_format and datetime_format values in the get_date_formats() function inside django/utils/translation/trans_real.py. It was dirty, but I had already been using a custom Django of sorts for that project, so didn’t see anything going wrong in hacking it trifle more.

According to my experiments with Django 4.2.1, DATETIME_FORMAT for DateTimeField() works only in Django Templates. In addition, DATE_FORMAT for DateField() and TIME_FORMAT for TimeField() work in Django Templates. *You can see my question explaining it.

And, DATE_INPUT_FORMATS for DateTimeField() and DateField() and TIME_INPUT_FORMATS for DateTimeField() and TimeField() work in Django Admin. *DATETIME_INPUT_FORMATS doesn’t work to any parts of a Django project and you can see my question explaining it.

*You need to set USE_L10N False in settings.py to make these settings above work because USE_L10N is prior to them.