.. index:: single: Controller; Customize error pages single: Error pages
When any exception is thrown in Symfony2, the exception is caught inside the
Kernel
class and eventually forwarded to a special controller,
TwigBundle:Exception:show
for handling. This controller, which lives
inside the core TwigBundle
, determines which error template to display and
the status code that should be set for the given exception.
Error pages can be customized in two different ways, depending on how much control you need:
- Customize the error templates of the different error pages (explained below);
- Replace the default exception controller
TwigBundle::Exception:show
with your own controller and handle it however you want (see :ref:`exception_controller in the Twig reference<config-twig-exception-controller>`);
Tip
The customization of exception handling is actually much more powerful
than what's written here. An internal event, kernel.exception
, is thrown
which allows complete control over exception handling. For more
information, see :ref:`kernel-kernel.exception`.
All of the error templates live inside TwigBundle
. To override the
templates, we simply rely on the standard method for overriding templates that
live inside a bundle. For more information, see
:ref:`overriding-bundle-templates`.
For example, to override the default error template that's shown to the
end-user, create a new template located at
app/Resources/TwigBundle/views/Exception/error.html.twig
:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>An Error Occurred: {{ status_text }}</title>
</head>
<body>
<h1>Oops! An Error Occurred</h1>
<h2>The server returned a "{{ status_code }} {{ status_text }}".</h2>
</body>
</html>
Tip
If you're not familiar with Twig, don't worry. Twig is a simple, powerful
and optional templating engine that integrates with Symfony2
. For more
information about Twig see :doc:`/book/templating`.
In addition to the standard HTML error page, Symfony provides a default error
page for many of the most common response formats, including JSON
(error.json.twig
), XML, (error.xml.twig
), and even Javascript
(error.js.twig
), to name a few. To override any of these templates, just
create a new file with the same name in the
app/Resources/TwigBundle/views/Exception
directory. This is the standard
way of overriding any template that lives inside a bundle.
You can also customize specific error templates according to the HTTP status
code. For instance, create a
app/Resources/TwigBundle/views/Exception/error404.html.twig
template to
display a special page for 404 (page not found) errors.
Symfony uses the following algorithm to determine which template to use:
- First, it looks for a template for the given format and status code (like
error404.json.twig
); - If it does not exist, it looks for a template for the given format (like
error.json.twig
); - If it does not exist, it falls back to the HTML template (like
error.html.twig
).
Tip
To see the full list of default error templates, see the
Resources/views/Exception
directory of the TwigBundle
. In a
standard Symfony2 installation, the TwigBundle
can be found at
vendor/symfony/symfony/src/Symfony/Bundle/TwigBundle
. Often, the easiest way
to customize an error page is to copy it from the TwigBundle
into
app/Resources/TwigBundle/views/Exception
and then modify it.
Note
The debug-friendly exception pages shown to the developer can even be
customized in the same way by creating templates such as
exception.html.twig
for the standard HTML exception page or
exception.json.twig
for the JSON exception page.