[Django]-Setting DEBUG = False causes 500 Error

I know this is late but I ended up here with a search for my error 500 with DEBUG=False, in my case it did turn out to be the ALLOWED_HOSTS but I was using os.environ.get('variable') to populate the hosts, I did not notice this until I enabled logging, you can log all errors to file with the below and it will log even when DEBUG=False:

# settings.py
LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'verbose': {
            'format' : "[%(asctime)s] %(levelname)s [%(name)s:%(lineno)s] %(message)s",
            'datefmt' : "%d/%b/%Y %H:%M:%S"
        },
        'simple': {
            'format': '%(levelname)s %(message)s'
        },
    },
    'handlers': {
        'file': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': 'mysite.log',
            'formatter': 'verbose'
        },
    },
    'loggers': {
        'django': {
            'handlers':['file'],
            'propagate': True,
            'level':'DEBUG',
        },
        'MYAPP': {
            'handlers': ['file'],
            'level': 'DEBUG',
        },
    }
}

I encountered the same issue just recently in Django 2.0. I was able to figure out the problem by setting DEBUG_PROPAGATE_EXCEPTIONS = True. See here: https://docs.djangoproject.com/en/2.0/ref/settings/#debug-propagate-exceptions

In my case, the error was ValueError: Missing staticfiles manifest entry for 'admin/css/base.css'. I fixed that by locally running python manage.py collectstatic.

In my case, reading docs of third party apps properly saved me.

The culprit? django_compressor

I had

{% load compress %}
{% compress css %}
 ... css files linked here ..
{% endcompress %}

DEBUG = True always gave me 500. To fix it, I needed a line in my settings to get it running

COMPRESS_ENABLED = os.environ.get('COMPRESS_ENABLED', False)

Its mid 2019 and I faced this error after a few years of developing with Django. Baffled me for an entire night! It wasn’t allowed host (which should throw a 400), everything else checked out, finally did some error logging only to discover that some missing / or messed up static files manifest (after collectstatic) were screwing with the setup. Long story short, for those who are stumped AND SO HAPPEN ARE USING WHITENOISE OR THE DJANGO STATICFILE BACKEND WITH CACHE (manifest static files) , maybe this is for you.

1. Make sure you setup everything (as I did for the whitenoise backend…django backends read on nonetheless) http://whitenoise.evans.io/en/stable/django.html

2. If error code 500 still shoots you down, take note on your settings.STATICFILES_STORAGE.

Set it to either (for whitenoise backend with compression)

STATICFILES_STORAGE = 'whitenoise.storage.CompressedStaticFilesStorage'

or (leave as django default)

STATICFILES_STORAGE = django.contrib.staticfiles.storage.StaticFilesStorage

All in all, THE PROBLEM seemed to come from the fact that this whitenoise cache + compression backend –>

STATICFILES_STORAGE = 'whitenoise.storage.CompressedManifestStaticFilesStorage'

or the django’s own caching backend –>

STATICFILES_STORAGE = 'django.contrib.staticfiles.storage.ManifestStaticFilesStorage'

…didnt quite work well for me, since my css was referencing some other sources which may be mixed up during collectstatic / backend caching. This issue is also potentially highlighted in http://whitenoise.evans.io/en/stable/django.html#storage-troubleshoot

Right, in Django 1.5 if DEBUG = False, configure ALLOWED_HOSTS, adding domains without the port number. example:

ALLOWED_HOSTS = ['localhost']

You must also check your URLs all over the place. When the DEBUG is set to False, all URLs without trailing / are treated as a bug, unlike when you have DEBUG = True, in which case Django will append / everywhere it is missing. So, in short, make sure all links end with a slash EVERYWHERE.

Complementing the main answer
It is annoying to change the ALLOWED_HOSTS and DEBUG global constants in settings.py when switching between development and production.
I am using this code to set these setting automatically:

import socket

if socket.gethostname() == "server_name":
    DEBUG = False
    ALLOWED_HOSTS = [".your_domain_name.com",]
    ...
else:
    DEBUG = True
    ALLOWED_HOSTS = ["localhost", "127.0.0.1",]
    ...

If you use macOS you could write a more generic code:

if socket.gethostname().endswith(".local"): # True in your local computer
    DEBUG = True
    ALLOWED_HOSTS = ["localhost", "127.0.0.1",]
else:
    ...

For what it’s worth – I was getting a 500 with DEBUG = False on some pages only. Tracing back the exception with pdb revealed a missing asset (I suspect the {% static ... %} template tag was the culprit for the 500.

I was searching and testing more about this issue and I realized that static files directories specified in settings.py can be a cause of this, so fist, we need to run this command

python manage.py collectstatic

in settings.py, the code should look something like this:

STATIC_URL = '/static/'

STATICFILES_DIRS = (
    os.path.join(BASE_DIR, 'static'),
)

STATIC_ROOT = os.path.join(BASE_DIR, 'staticfiles')

I have a hilarious story for all. After reaching this page I said “Eureka! I’m saved. That MUST be my problem.” So I inserted the required ALLOWED_HOSTS list in setting.py and… nothing. Same old 500 error. And no, it wasn’t for lack of a 404.html file.

So for 2 days I busied myself with wild theories, such as that it had something to do with serving static files (understand that I am a noob and noobs don’t know what they’re doing).

So what was it? It is now Mr. Moderator that we come to a useful tip. Whereas my development Django is version 1.5.something, my production server version is 1.5.something+1… or maybe plus 2. Whatever. And so after I added the ALLOWED_HOSTS to the desktop version of settings.py, which lacked what hwjp requested— a “default value in settings.py, perhaps with an explanatory comment”— I did the same on the production server with the proper domain for it.

But I failed to notice that on the production server with the later version of Django there WAS a default value in settings.py with an explanatory comment. It was well below where I made my entry, out of sight on the monitor. And of course the list was empty. Hence my waste of time.

ALLOWED_HOSTS is NOT the only issue, for me I had to make a 404.html and put it in the base level of my templates (not app level) – Also, you can make a 404 view and add a 404handler url but I think thats optional. 404.html fixed it

in mainproject.urls

handler404 = 'app.views.custom_404'

in app.views

def custom_404(request):
    return render(request, '404.html', {}, status=404)

then make a templates/404.html template

got this from another S/O post that I cannot find it

EDIT

also, I get 500 errors when I serve assets with whitenoise. Could not figure that out for the life of me, error was ValueError from whitenoise not being able to find an asset that I also could not find, had to go with default django serving for now

I know that this is a super old question, but maybe I could help some one else. If you are having a 500 error after setting DEBUG=False, you can always run the manage.py runserver in the command line to see any errors that wont appear in any web error logs.

I faced the same problem when I did DEBUG = FALSE. Here is a consolidated solution as scattered in answers above and other posts.

By default, in settings.py we have ALLOWED_HOSTS = [] . Here are possible changes you will have to make in ALLOWED_HOSTS value as per scenario to get rid of the error:

1: Your domain name:

ALLOWED_HOSTS = ['www.example.com'] # Your domain name here

2: Your deployed server IP if you don’t have domain name yet (which was my case and worked like a charm):

ALLOWED_HOSTS = ['123.123.198.123'] # Enter your IP here

3: If you are testing on local server, you can edit your settings.py or settings_local.py as:

ALLOWED_HOSTS = ['localhost', '127.0.0.1']

4: You can also provide ‘*’ in the ALLOWED_HOSTS value but its not recommended in the production environment due to security reasons:

ALLOWED_HOSTS = ['*'] # Not recommended in production environment

I have also posted a detailed solution on my blog which you may want to refer.

I know this post is quite old but it’s still perfectly relevant today.

For what it’s worth – I was getting a 500 with DEBUG = False for all pages on my site.

I got no traceback when in debug.

I had to go through every static link in my templates within my site and found one / (forward slash) in front of my image source. {% static … %}. This caused the 500 error in DEBUG = False but worked perfectly fine in Debug = True with no errors. Very annoying! Be warned! Many hours of time wasted due to a forward slash…

You might want to run python manage.py collectstatic after you set DEBUG = False and ALLOWED_HOSTS = ['127.0.0.1'] in settings.py. After these two steps my web application ran well in my local server even with DEBUG=False mode.

BTW I have these settings in settings.py.

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'whitenoise.middleware.WhiteNoiseMiddleware', # what i added
    'django.middleware.common.CommonMiddleware', # and so on...
]

STATICFILES_STORAGE = 'whitenoise.storage.CompressedManifestStaticFilesStorage'

I assume maybe whitenoise setting has something to do with collectstatic command.

I have the similar issue, in my case it was caused by having a Commented script inside the body tag.

<!--<script>  </script>-->

I think it could also be the http server settings. Mine is still broken and had ALLOWED_HOSTS the entire time. I can access it locally (i use gunicorn), but not via the domain name when DEBUG=False. when I try using the domain name it then gives me the error, so makes me think its a nginx related issue.

Here is my conf file for nginx:

server {
    listen   80;
    server_name localhost myproject.ca www.myproject.ca;
    root /var/web/myproject/deli_cms;

    # serve directly - analogous for static/staticfiles
    location /media/ {
        # if asset versioning is used
        if ($query_string) {
            expires max;
        }
    }
    location /admin/media/ {
        # this changes depending on your python version
        root /var/web/myproject/lib/python2.6/site-packages/django/contrib;
    }
    location /static/ {
    alias /var/web/myproject/deli_cms/static_root/;
    }

    location / {
        proxy_pass_header Server;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Scheme $scheme;
        proxy_connect_timeout 10;
        proxy_read_timeout 10;
        proxy_pass http://localhost:8000/;
    }
    # what to serve if upstream is not available or crashes
    error_page 500 502 503 504 /media/50x.html;
}

A bit late to the party, and off course there could be a legion of issues but I’ve had a similar issue and it turned out that I had {% %} special characters inside my html remark…

<!-- <img src="{% static "my_app/myexample.jpg" %}" alt="My image"/> -->

I ran into this issue. Turns out I was including in the template, using the static template tag, a file that did not exist anymore. A look in the logs showed me the problem.

I guess this is just one of many possible reasons for this kind of error.

Moral of the story: always log errors and always check logs.

Thanks to @squarebear, in the log file, I found the error:
ValueError: The file 'myapp/styles.css' could not be found with <whitenoise.storage.CompressedManifestStaticFilesStorage ...>.

I had a few problems in my django app. I removed the line
STATICFILES_STORAGE = 'whitenoise.django.GzipManifestStaticFilesStorage' which I found from the heroku’s documentation.

I also had to add extra directory (thanks to another SO answer) static in the root of django application as myapp/static even though I wasn’t using it. Then running the command python manage.py collectstatic before running the server solved the problem. Finally, it started working fine.

this maybe help someone else, in my case the problem with the missing favicon.

I know this is an old question, but I was also getting a 500 error when DEBUG=False. After several hours, I realized I had forgot to end some of the links in my base.html with a trailing slash.

This is old and my problem ended up being related to the problem but not for the OP but my solution is for anyone else who tried the above to no avail.

I had a setting in a modified version of Django to minify CSS and JS files that only ran when DEBUG was off. My server did not have the CSS minifier installed and threw the error. If you are using Django-Mako-Plus, this might be your issue.

One small thing to note, If the array has None in it, then all the subsequent allowed hosts are ignored.

ALLOWED_HOSTS = [
    "localhost",
    None,
    'example.com', # First DNS alias (set up in the app)
    #'www.example.com', # Second DNS alias (set up in the app)
]

Django version 1.8.4

I had one view that threw a 500 error in debug=false but worked in debug=true. For anyone who is getting this kind of thing and Allowed Hosts is not the problem, I fixed my view by updating a template’s static tag that was pointing to the wrong location.

So I’d suggest just checking links and tags are airtight in any templates used, maybe certain things slip through the net in debug but give errors in production.

I found yet another cause of the 500 error when DEBUG=False. I use the Django compressor utility and our front-end engineer added references to font files inside a compress css block in a Django template. Like this:

{% compress css %}
    <link href="{% static "css/bootstrap.css" %}" rel="stylesheet">
    <link href="{% static "css/bootstrap-spinedit.css" %}" rel="stylesheet">
    <link href="{% static "djangular/css/styles.css" %}" rel="stylesheet">
    <link href="{% static "fonts/fontawesome-webfont.ttf" %}" rel="stylesheet">
{% endcompress %}

The solution was to move the link to the ttf file below the endcompress line.

I had a problem similar to this and I will report how I solved mine because it could be that someone is also experiencing the same.

In my case, the error was caused because the server was not finding some static files from the homepage.

So make sure the error only occurs in the index or occurs on another page. If the problem is only occurring in the index very probably you need to check the static files. I recommend opening the Chrome preview console and checking for any errors.

In my case, the server couldn’t find favicon.ico and two other CSS.

To fix this I passed python manage.py collectstatic and it worked.

I started to get the 500 for debug=False in the form of

django.urls.exceptions.NoReverseMatch: Reverse for 'home' not found.
or...
django.urls.exceptions.NoReverseMatch: Reverse for 'about' not found.

when raising django.core.exceptions.ValidationError instead of raising rest_framework.serializers.ValidationError

To be fair, it was already raising a 500 before, but as a ValidationError, with debug=False, this changed into the NoReverseMatch.

I had this issue and solved it by removing this line:
STATICFILES_STORAGE = "whitenoise.storage.CompressedManifestStaticFilesStorage

my problem was in wrong 404.html template – I copy&pasted

<a href="{% url 'home:index' %}">

instead of (in my case)

 <a href="{% url 'posts:index' %}">

that’s why 500 apperar

Ok after trying soo many things, the correct solution is …

you need to set DEBUG = 'FALSE' not False or FALSE, but 'FALSE' with ''

If you want to allow for all hosts.
Use ALLOWED_HOSTS = [‘*’,]
instead of
ALLOWED_HOSTS = [‘*’]