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How to Optimize your Development Environment for Debugging

How to Optimize your Development Environment for Debugging

When you work on a Symfony project on your local machine, you should use the dev environment (app_dev.php front controller). This environment configuration is optimized for two main purposes:

  • Give the developer accurate feedback whenever something goes wrong (web debug toolbar, nice exception pages, profiler, …);
  • Be as similar as possible as the production environment to avoid problems when deploying the project.

Disabling the Bootstrap File and Class Caching

And to make the production environment as fast as possible, Symfony creates big PHP files in your cache containing the aggregation of PHP classes your project needs for every request. However, this behavior can confuse your debugger, because the same class can be located in two different places: the original class file and the big file which aggregates lots of classes.

This recipe shows you how you can tweak this caching mechanism to make it friendlier when you need to debug code that involves Symfony classes.

The app_dev.php front controller reads as follows by default:

// ...

$loader = require __DIR__.'/../app/autoload.php';

$kernel = new AppKernel('dev', true);
$request = Request::createFromGlobals();
// ...

To make your debugger happier, disable the loading of all PHP class caches by removing the call to loadClassCache():

// ...

$loader = require_once __DIR__.'/../app/autoload.php';

$kernel = new AppKernel('dev', true);
// $kernel->loadClassCache();
$request = Request::createFromGlobals();


If you disable the PHP caches, don’t forget to revert after your debugging session.

Some IDEs do not like the fact that some classes are stored in different locations. To avoid problems, you can either tell your IDE to ignore the PHP cache files, or you can change the extension used by Symfony for these files:

$kernel->loadClassCache('classes', '.php.cache');

Deprecated since version 3.3: The loadClassCache() was deprecated in Symfony 3.3 and removed in Symfony 4.0. No alternative is provided because this feature is useless when using PHP 7 or higher.

Useful Debugging Commands

When developing a large application, it can be hard to keep track of all the different services, routes and translations. Luckily, Symfony has some commands that can help you visualize and find the information.

Shows information about the current project, such as the Symfony version, the Kernel and PHP.
Displays information about the contents of the Symfony container for all public services. To find only those matching a name, append the name as an argument.
Shows all configured bundles, their class and their alias.
Displays information about form types and their options.
Displays information about all the registered listeners in the event dispatcher.
Displays information about all configured routes in the application as a table with the name, method, scheme, host and path for each route.
debug:translation <locale>
Shows a table of the translation key, the domain, the translation and the fallback translation for all known messages, if translations exist for the given locale.


When in doubt how to use a console command, open the help section by appending the --help option.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.