CommandError: You must set settings.ALLOWED_HOSTS if DEBUG is False

Question

Try

ALLOWED_HOSTS = ['*']

Less secure if you're not firewalled off or on a public LAN, but it's what I use and it works.

EDIT: Interestingly enough I've been needing to add this to a few of my 1.8 projects even when DEBUG = True. Very unsure why.

EDIT: This is due to a Django security update as mentioned in my comment.

Your solution might be to add the original IP and/or hostname also:

ALLOWED_HOSTS = [
  'localhost',
  '127.0.0.1',
  '111.222.333.444',
  'mywebsite.com']

The condition to be satisfied is that the host header (or X-Forwarded-Host if USE_X_FORWARDED_HOST is enabled) should match one of the values in ALLOWED_HOSTS.

Make sure it's not redefined again lower down in your settings.py. The default settings has:

ALLOWED_HOSTS = []

From documentation: https://docs.djangoproject.com/en/1.10/ref/settings/

if DEBUG is False, you also need to properly set the ALLOWED_HOSTS setting. Failing to do so will result in all requests being returned as “Bad Request (400)”.

And from here: https://docs.djangoproject.com/en/1.10/ref/settings/#std:setting-ALLOWED_HOSTS

I am using something like this:

ALLOWED_HOSTS = ['localhost', '127.0.0.1', 'www.mysite.com']

Use this:

ALLOWED_HOSTS =  ['localhost', '127.0.0.1']

If you work in PyCharm, check the Environmental variables for your Django server. You should specify the proper module.settings file

This works for me:

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = False

ALLOWED_HOSTS = ['localhost', '127.0.0.1']