---
title: "Debugging"
manual: "TYPO3 Explained"
version: "main"
permalink: "https://docs.typo3.org/permalink/t3coreapi:examples-debug@main"
source: "ApiOverview/Debugging/Index.rst"
modified: "2026-09-15T12:49:12+00:00"
---

# Debugging

-   [PHP](https://docs.typo3.org/permalink/t3coreapi:php@main)
-   [TYPO3 backend debug mode](https://docs.typo3.org/permalink/t3coreapi:typo3-backend-debug-mode@main)
-   [Extbase DebuggerUtility](https://docs.typo3.org/permalink/t3coreapi:extbase-debuggerutility@main)
-   [Fluid debug ViewHelper](https://docs.typo3.org/permalink/t3coreapi:fluid-debug-viewhelper@main)
-   [Xdebug](https://docs.typo3.org/permalink/t3coreapi:xdebug@main)

## PHP

## TYPO3 backend debug mode

To display additional debug information in the backend, set
[$GLOBALS\['TYPO3_CONF_VARS'\]\['BE'\]\['debug'\]](https://docs.typo3.org/permalink/t3coreapi:typo3confvars-be-debug@main)
in `config/system/settings.php` and log in with an administrator
account.

In a development context you may want to set debug mode to true for extended periods. This can be achieved by altering the setting in `config/system/additional.php`. To prevent deploying to production, you can use an environment variable or check the environment context before overriding the setting in `config/system/settings.php`.

It shows for example the names of fields and in case of select, radio and
checkbox fields the values in addition, which are generated by the
[FormEngine](https://docs.typo3.org/permalink/t3coreapi:formengine@main). These can be used to set access permissions or
configuration using [Page TSconfig](https://docs.typo3.org/m/typo3/reference-typoscript/main/en-us/PageTsconfig/Index.html#pagetsconfig).

If [EXT:lowlevel](https://docs.typo3.org/c/typo3/cms-lowlevel/main/en-us/Index.html) is installed, the name of the
database table or field is appended to the select options in the
**System > Database > Full Search** module.

### `DebugUtility::debug()`

The TYPO3 Core provides a simple `debug()` (defined in
`EXT:core/Classes/Core/GlobalDebugFunctions.php`). It wraps around
`\TYPO3\CMS\Core\Utility\DebugUtility::debug()` and will output debug
information only if it matches a set of IP addresses (defined in
[$GLOBALS\['TYPO3_CONF_VARS'\]\['SYS'\]\['devIPmask'\]](https://docs.typo3.org/permalink/t3coreapi:typo3confvars-sys-devipmask@main)).

For example, the following code:

**Extension examples, file Classes/Controller/ModuleController.php**

```php
<?php

use TYPO3\CMS\Core\Utility\DebugUtility;

class ModuleController extends ActionController implements LoggerAwareInterface
{
  protected function debugCookies()
  {
    DebugUtility::debug($_COOKIE, 'cookie');
  }
}

```

will produce such an output:

![](../../Images/ManualScreenshots/Examples/Debugging/DebugOutput.png)

In general, look at class `\TYPO3\CMS\Core\Utility\DebugUtility` for useful
debugging tools.

## Extbase `DebuggerUtility`

Extbase's DebuggerUtility::var_dump() is a debugging function in TYPO3 that outputs detailed, human-readable information about variables, including their type and structure. It offers features like depth control and optional backtrace information to assist developers in effectively debugging complex data structures.

**Example:**

`\TYPO3\CMS\Extbase\Utility\DebuggerUtility::var_dump($myVariable);`

You can also use the Extbase DebuggerUtility to debug SQL Querys for example. To do so, put the following code snippet before the execute function of your SQL query:

`\TYPO3\CMS\Extbase\Utility\DebuggerUtility::var_dump($queryBuilder->getSQL());`

## Fluid debug ViewHelper

The Fluid Debug ViewHelper is a part of the Fluid template engine and generates a HTML dump of the tagged variable. The ViewHelper can be used in any Fluid template to output the value of variables or objects in a human-readable format.

**Example:**

`<f:debug>{myVariable}</f:debug>`

To display all available variables in your Fluid template, you can use the \_all placeholder:

`<f:debug>{_all}</f:debug>`

> [!NOTE]
> If you are debugging in a Fluid partial or a Fluid section, make sure that all variables you want to analyse are passed (defined in the arguments attribute of the render tag).

Get more information in the Fluid ViewHelper Reference [Debug ViewHelper \<f:debug>](https://docs.typo3.org/other/typo3/view-helper-reference/main/en-us/Global/Debug.html#typo3-fluid-debug)

## Xdebug

First of all: best practice to debug PHP code is using an IDE (like [PhpStorm](https://www.jetbrains.com/phpstorm/)
or [Visual Studio Code](https://code.visualstudio.com/)) with [Xdebug](https://xdebug.org/). Advantages are:

-   You can investigate the values of variables and class properties when
    setting a breakpoint.
-   You can move forward line by line and see how the variables and properties
    change.
-   You can also step into calling methods and functions.
-   You see the calling code as a stack trace.

> [!NOTE]
> **See also**
>
> -   [Configure Xdebug in PhpStorm](https://www.jetbrains.com/help/phpstorm/configuring-xdebug.html)
> -   [Configure Xdebug in Visual Studio Code](https://tommcfarlin.com/xdebug-in-visual-studio-code/)