explaingit

symfony/debug

★ 7,193PHPAudience · developerComplexity · 2/5Setup · easy

TLDR

A deprecated Symfony PHP component that displayed structured, readable error messages during development, superseded by the ErrorHandler component since Symfony 4.4 in 2019 and no longer receiving updates.

Mindmap

mindmap
  root((symfony/debug))
    What it does
      Better PHP error display
      Development mode helper
      Single function activation
    Status
      Deprecated since 4.4
      No more updates
      Replace with ErrorHandler
    Tech stack
      PHP
      Composer
      Symfony framework
    Use cases
      Legacy project support
      Migration to ErrorHandler
    Audience
      PHP developers
      Symfony users
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Things people build with this

USE CASE 1

Migrate a legacy project still using symfony/debug to the modern symfony/error-handler component to restore security patches and updates.

USE CASE 2

Understand how Symfony's error display has evolved when maintaining an older codebase that still depends on this deprecated package.

Tech stack

PHPComposerSymfony

Getting it running

Difficulty · easy Time to first run · 5min

Deprecated since Symfony 4.4, receives no updates or security patches, migrate to symfony/error-handler before using in any active project.

No license information is provided in this explanation.

In plain English

symfony/debug is a PHP component from the Symfony project, a popular framework for building web applications. Its purpose was to improve error handling during development: rather than the plain, hard-to-read error messages PHP produces by default, this component displayed them in a more structured and readable format, making it easier to locate the source of a problem in your code. Symfony packages its functionality into small, independent components that can be installed separately. You install this one with Composer, PHP's standard package manager, and activate it with a single function call in your application's bootstrap code. However, this component is deprecated. The README states plainly that symfony/debug has been deprecated since Symfony 4.4, released in 2019, and that the ErrorHandler component is its replacement. Deprecated means the code still exists and may still work, but it will no longer receive updates, bug fixes, or security patches. Any project currently using symfony/debug is expected to migrate to the ErrorHandler component instead. The README itself is very short: one installation command, one code example showing how to enable it, and links to Symfony's main issue tracker for reporting problems. The fuller documentation and integration examples have always lived in Symfony's central documentation site rather than in this standalone repository. Given that this package is no longer under active development, its star count of over 7,000 reflects its historical use during the years when it was Symfony's standard debugging component, rather than any current activity.

Copy-paste prompts

Prompt 1
I have an old Symfony 4.3 project still using symfony/debug. Walk me through migrating it to the ErrorHandler component step by step.
Prompt 2
Show me the Composer commands to remove symfony/debug and add symfony/error-handler, plus the code change to re-enable structured error display in my bootstrap file.
Prompt 3
My project uses symfony/debug to catch PHP errors on startup. Rewrite that bootstrap code to use the ErrorHandler component instead.
Prompt 4
What are the key differences between symfony/debug and symfony/error-handler, and which features were dropped versus carried over?
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