RuntimeWarning: DateTimeField received a naive datetime

The problem is not in Django settings, but in the date passed to the model. Here's how a timezone-aware object looks like:

>>> from django.utils import timezone
>>> import pytz
>>> timezone.now()
datetime.datetime(2013, 11, 20, 20, 8, 7, 127325, tzinfo=pytz.UTC)

And here's a naive object:

>>> from datetime import datetime
>>> datetime.now()
datetime.datetime(2013, 11, 20, 20, 9, 26, 423063)

So if you are passing email date anywhere (and it eventually gets to some model), just use Django's now(). If not, then it's probably an issue with an existing package that fetches date without timezone and you can patch the package, ignore the warning or set USE_TZ to False.

Use django.utils.timezone.make_aware function to make your naive datetime objects timezone aware and avoid those warnings.

It converts naive datetime object (without timezone info) to the one that has timezone info (using timezone specified in your django settings if you don't specify it explicitly as a second argument):

import datetime
from django.conf import settings
from django.utils.timezone import make_aware

naive_datetime = datetime.datetime.now()
naive_datetime.tzinfo  # None

settings.TIME_ZONE  # 'UTC'
aware_datetime = make_aware(naive_datetime)
aware_datetime.tzinfo  # <UTC>

Just to fix the error to set current time

from django.utils import timezone
import datetime

datetime.datetime.now(tz=timezone.utc) # you can use this value

Quick and dirty - Turn it off:

USE_TZ = False

in your settings.py

One can both fix the warning and use the timezone specified in settings.py, which might be different from UTC.

For example in my settings.py I have:

USE_TZ = True
TIME_ZONE = 'Europe/Paris'

Here is a solution; the advantage is that str(mydate) gives the correct time:

>>> from datetime import datetime
>>> from django.utils.timezone import get_current_timezone
>>> mydate = datetime.now(tz=get_current_timezone())
>>> mydate
datetime.datetime(2019, 3, 10, 11, 16, 9, 184106, 
    tzinfo=<DstTzInfo 'Europe/Paris' CET+1:00:00 STD>)
>>> str(mydate)
'2019-03-10 11:16:09.184106+01:00'

Another equivalent method is using make_aware, see dmrz post.

make sure settings.py has USE_TZ = True

In your python file:

from django.utils import timezone

timezone.now() # use its value in model field

If you are trying to transform a naive datetime into a datetime with timezone in django, here is my solution:

>>> import datetime
>>> from django.utils import timezone
>>> t1 = datetime.datetime.strptime("2019-07-16 22:24:00", "%Y-%m-%d %H:%M:%S")
>>> t1
    datetime.datetime(2019, 7, 16, 22, 24)
>>> current_tz = timezone.get_current_timezone()
>>> t2 = current_tz.localize(t1)
>>> t2
    datetime.datetime(2019, 7, 16, 22, 24, tzinfo=<DstTzInfo 'Asia/Shanghai' CST+8:00:00 STD>)
>>>

t1 is a naive datetime and t2 is a datetime with timezone in django's settings.

You can also override settings, particularly useful in tests:

from django.test import override_settings

with override_settings(USE_TZ=False):
    # Insert your code that causes the warning here
    pass

This will prevent you from seeing the warning, at the same time anything in your code that requires a timezone aware datetime may give you problems. If this is the case, see kravietz answer.

In the model, do not pass the value:

timezone.now()

Rather, remove the parenthesis, and pass:

timezone.now

If you continue to get a runtime error warning, consider changing the model field from DateTimeField to DateField.