# Django 1.8.18.dev20170123152445 documentation

# Error reporting

When you’re running a public site you should always turn off the `DEBUG` setting. That will make your server run much faster, and will also prevent malicious users from seeing details of your application that can be revealed by the error pages.

However, running with `DEBUG` set to `False` means you’ll never see errors generated by your site – everyone will just see your public error pages. You need to keep track of errors that occur in deployed sites, so Django can be configured to create reports with details about those errors.

## Email reports

### Server errors

When `DEBUG` is `False`, Django will email the users listed in the `ADMINS` setting whenever your code raises an unhandled exception and results in an internal server error (HTTP status code 500). This gives the administrators immediate notification of any errors. The `ADMINS` will get a description of the error, a complete Python traceback, and details about the HTTP request that caused the error.

Note

In order to send email, Django requires a few settings telling it how to connect to your mail server. At the very least, you’ll need to specify `EMAIL_HOST` and possibly `EMAIL_HOST_USER` and `EMAIL_HOST_PASSWORD`, though other settings may be also required depending on your mail server’s configuration. Consult the Django settings documentation for a full list of email-related settings.

By default, Django will send email from root@localhost. However, some mail providers reject all email from this address. To use a different sender address, modify the `SERVER_EMAIL` setting.

To activate this behavior, put the email addresses of the recipients in the `ADMINS` setting.

See also

Server error emails are sent using the logging framework, so you can customize this behavior by customizing your logging configuration.

### 404 errors

Django can also be configured to email errors about broken links (404 “page not found” errors). Django sends emails about 404 errors when:

- `DEBUG` is `False`;
- Your `MIDDLEWARE_CLASSES` setting includes `django.middleware.common.BrokenLinkEmailsMiddleware`.

If those conditions are met, Django will email the users listed in the `MANAGERS` setting whenever your code raises a 404 and the request has a referer. (It doesn’t bother to email for 404s that don’t have a referer – those are usually just people typing in broken URLs or broken Web ‘bots).

Note

`BrokenLinkEmailsMiddleware` must appear before other middleware that intercepts 404 errors, such as `LocaleMiddleware` or `FlatpageFallbackMiddleware`. Put it towards the top of your `MIDDLEWARE_CLASSES` setting.

You can tell Django to stop reporting particular 404s by tweaking the `IGNORABLE_404_URLS` setting. It should be a tuple of compiled regular expression objects. For example:

    import re
    IGNORABLE_404_URLS = (
        re.compile(r'\.(php|cgi)$'),
        re.compile(r'^/phpmyadmin/'),
    )

In this example, a 404 to any URL ending with `.php` or `.cgi` will not be reported. Neither will any URL starting with `/phpmyadmin/`.

The following example shows how to exclude some conventional URLs that browsers and crawlers often request:

    import re
    IGNORABLE_404_URLS = (
        re.compile(r'^/apple-touch-icon.*\.png$'),
        re.compile(r'^/favicon\.ico$'),
        re.compile(r'^/robots\.txt$'),
    )

(Note that these are regular expressions, so we put a backslash in front of periods to escape them.)

If you’d like to customize the behavior of `django.middleware.common.BrokenLinkEmailsMiddleware` further (for example to ignore requests coming from web crawlers), you should subclass it and override its methods.

See also

404 errors are logged using the logging framework. By default, these log records are ignored, but you can use them for error reporting by writing a handler and configuring logging appropriately.

## Filtering error reports

Warning

Filtering sensitive data is a hard problem, and it’s nearly impossible to guarantee that sensitive won’t leak into an error report. Therefore, error reports should only be available to trusted team members and you should avoid transmitting error reports unencrypted over the Internet (such as through email).

### Filtering sensitive information

Error reports are really helpful for debugging errors, so it is generally useful to record as much relevant information about those errors as possible. For example, by default Django records the full traceback for the exception raised, each traceback frame’s local variables, and the `HttpRequest`’s attributes.

However, sometimes certain types of information may be too sensitive and thus may not be appropriate to be kept track of, for example a user’s password or credit card number. So Django offers a set of function decorators to help you control which information should be filtered out of error reports in a production environment (that is, where `DEBUG` is set to `False`): `sensitive_variables()` and `sensitive_post_parameters()`.

`sensitive_variables`(*variables)

  If a function (either a view or any regular callback) in your code uses local variables susceptible to contain sensitive information, you may prevent the values of those variables from being included in error reports using the `sensitive_variables` decorator:

      from django.views.decorators.debug import sensitive_variables

      @sensitive_variables('user', 'pw', 'cc')
      def process_info(user):
          pw = user.pass_word
          cc = user.credit_card_number
          name = user.name
          ...

  In the above example, the values for the `user`, `pw` and `cc` variables will be hidden and replaced with stars (**********) in the error reports, whereas the value of the `name` variable will be disclosed.

  To systematically hide all local variables of a function from error logs, do not provide any argument to the `sensitive_variables` decorator:

      @sensitive_variables()
      def my_function():
          ...

  When using multiple decorators

  If the variable you want to hide is also a function argument (e.g. ‘`user`’ in the following example), and if the decorated function has multiple decorators, then make sure to place `@sensitive_variables` at the top of the decorator chain. This way it will also hide the function argument as it gets passed through the other decorators:

      @sensitive_variables('user', 'pw', 'cc')
      @some_decorator
      @another_decorator
      def process_info(user):
          ...

`sensitive_post_parameters`(*parameters)

  If one of your views receives an `HttpRequest` object with `POST parameters` susceptible to contain sensitive information, you may prevent the values of those parameters from being included in the error reports using the `sensitive_post_parameters` decorator:

      from django.views.decorators.debug import sensitive_post_parameters

      @sensitive_post_parameters('pass_word', 'credit_card_number')
      def record_user_profile(request):
          UserProfile.create(user=request.user,
                             password=request.POST['pass_word'],
                             credit_card=request.POST['credit_card_number'],
                             name=request.POST['name'])
          ...

  In the above example, the values for the `pass_word` and `credit_card_number` POST parameters will be hidden and replaced with stars (**********) in the request’s representation inside the error reports, whereas the value of the `name` parameter will be disclosed.

  To systematically hide all POST parameters of a request in error reports, do not provide any argument to the `sensitive_post_parameters` decorator:

      @sensitive_post_parameters()
      def my_view(request):
          ...

  All POST parameters are systematically filtered out of error reports for certain `django.contrib.auth.views` views (`login`, `password_reset_confirm`, `password_change`, and `add_view` and `user_change_password` in the `auth` admin) to prevent the leaking of sensitive information such as user passwords.

### Custom error reports

All `sensitive_variables()` and `sensitive_post_parameters()` do is, respectively, annotate the decorated function with the names of sensitive variables and annotate the `HttpRequest` object with the names of sensitive POST parameters, so that this sensitive information can later be filtered out of reports when an error occurs. The actual filtering is done by Django’s default error reporter filter: `django.views.debug.SafeExceptionReporterFilter`. This filter uses the decorators’ annotations to replace the corresponding values with stars (**********) when the error reports are produced. If you wish to override or customize this default behavior for your entire site, you need to define your own filter class and tell Django to use it via the `DEFAULT_EXCEPTION_REPORTER_FILTER` setting:

    DEFAULT_EXCEPTION_REPORTER_FILTER = 'path.to.your.CustomExceptionReporterFilter'

You may also control in a more granular way which filter to use within any given view by setting the `HttpRequest`’s `exception_reporter_filter` attribute:

    def my_view(request):
        if request.user.is_authenticated():
            request.exception_reporter_filter = CustomExceptionReporterFilter()
        ...

Your custom filter class needs to inherit from `django.views.debug.SafeExceptionReporterFilter` and may override the following methods:

class `SafeExceptionReporterFilter`

`SafeExceptionReporterFilter.``is_active`(request)

  Returns `True` to activate the filtering operated in the other methods. By default the filter is active if `DEBUG` is `False`.

`SafeExceptionReporterFilter.``get_request_repr`(request)

  Returns the representation string of the request object, that is, the value that would be returned by `repr(request)`, except it uses the filtered dictionary of POST parameters as determined by `SafeExceptionReporterFilter.get_post_parameters()`.

`SafeExceptionReporterFilter.``get_post_parameters`(request)

  Returns the filtered dictionary of POST parameters. By default it replaces the values of sensitive parameters with stars (**********).

`SafeExceptionReporterFilter.``get_traceback_frame_variables`(request, tb_frame)

  Returns the filtered dictionary of local variables for the given traceback frame. By default it replaces the values of sensitive variables with stars (**********).

See also

You can also set up custom error reporting by writing a custom piece of exception middleware. If you do write custom error handling, it’s a good idea to emulate Django’s built-in error handling and only report/log errors if `DEBUG` is `False`.