What could cause a Django error when debug=False that isn't there when debug=True

Question

Using the development server, it works with debug=True or False.

In production, everything works if debug=True, but if debug=False, I get a 500 error and the apache logs end with an import error: "ImportError: cannot import name Project".

Nothing in the import does anything conditional on debug - the only code that does is whether the development server should serve static files or not (in production, apache should handle this - and this is tested separately and works fine).

Answer 1

Just to say, I ran into a similar error today and it's because Django 1.5 requires the ALLOWED_HOSTS parameter in the settings. You simply need to place this row to make it work ;)

...
ALLOWED_HOSTS = '*'
...

However, be aware that you need to set this parameter properly according to your actual host(s) (https://docs.djangoproject.com/en/dev/ref/settings/#allowed-hosts)!

Values in this list can be fully qualified names (e.g. 'www.example.com'), in which case they will be matched against the request’s Host header exactly (case-insensitive, not including port). A value beginning with a period can be used as a subdomain wildcard: '.example.com' will match example.com, www.example.com, and any other subdomain of example.com. A value of '*' will match anything; in this case you are responsible to provide your own validation of the Host header (perhaps in a middleware; if so this middleware must be listed first in MIDDLEWARE_CLASSES).

So basically it's better for you to use this type of configuration once you're in production:

...
ALLOWED_HOSTS = [
    '.yourdomain.com',
]
...

thanks to gertvdijk for pointing this out