Deprecation handling: logging, marking and finding deprecations

TYPO3 logs calls to deprecated functions to help developers identify and update outdated code. Deprecated methods will be removed in future TYPO3 versions, so they should be avoided.

Deprecations are triggered by trigger_error() and pass through TYPO3’s logging and exception system. In development, they are shown as exceptions by default; in production, they are typically ignored.

Note

For information how to handle deprecations in the TYPO3 Core, see the Contribution Guide: How to deprecate classes, methods, arguments and hooks in the TYPO3 core.

Table of content

Enabling the deprecation log

TYPO3 ships with a default configuration where deprecation logging is disabled. If you upgrade to the latest TYPO3 version, you need to change your development configuration to enable deprecation logging if you need it.

Via GUI

Enabling the deprecation log can be done in the Admin Tools > Settings backend module. Click on Choose Preset in the Configuration Presets pane, open Debug settings, activate the Debug option and submit with Activate preset. Disabling the deprecation log can be done by selecting the Live preset instead.

The debug preset also enables some other debug settings.

Note

These steps only enable/disable the FileWriter, which comes with the TYPO3 default configuration. If you manually configured additional writers for the TYPO3.CMS.deprecations logger, you need to manually remove them to completely disable deprecation logging.

Via configuration file directly

Instead of using the GUI you can also enable or disable the deprecation log with the disabled option:

Excerpt of config/system/settings.php | typo3conf/system/settings.php

<?php

return [
    // ... some configuration
    'LOG' => [
        'TYPO3' => [
            'CMS' => [
                'deprecations' => [
                    'writerConfiguration' => [
                        'notice' => [
                            'TYPO3\CMS\Core\Log\Writer\FileWriter' => [
                                'disabled' => false,
                            ],
                        ],
                    ],
                ],
            ],
        ],
    ],
    // ... more configuration
];

Deprecation logging can also be enabled in the additional.php configuration file, here with safeguarding to only enable it in development context:

config/system/additional.php | typo3conf/system/additional.php

<?php

use Psr\Log\LogLevel;
use TYPO3\CMS\Core\Core\Environment;
use TYPO3\CMS\Core\Log\Writer\FileWriter;

if (Environment::getContext()->isDevelopment()) {
    $GLOBALS['TYPO3_CONF_VARS']['LOG']['TYPO3']['CMS']['deprecations']
    ['writerConfiguration'][LogLevel::NOTICE][FileWriter::class]
    ['disabled'] = false;
}

For more information on how to configure the writing of deprecation logs see Writer configuration.

Find calls to deprecated functions

The extension scanner provides an interactive interface to scan extension code for usage of removed or deprecated TYPO3 Core API.

It is also possible to do a file search for @deprecated and E_USER_DEPRECATED. Using an IDE you can find all calls to the affected methods.

The deprecations are also listed in the changelog of the corresponding TYPO3 version.

Deprecate functions in extensions

Methods that will be removed in future versions of your extension should be marked as deprecated by both the doc comment and a call to the PHP error method:

Excerpt of EXT:my_extension/Classes/MyClass.php

/**
 * @deprecated since version 3.0.4, will be removed in version 4.0.0
 */
public function decreaseColPosCountByRecord(array $record, int $dec = 1): int
{
    trigger_error(
        'Method "decreaseColPosCountByRecord" is deprecated since version 3.0.4, will be removed in version 4.0.0',
        E_USER_DEPRECATED
    );

    // ... more logic
}

For more information about how to deprecate classes, arguments and hooks and how the TYPO3 Core handles deprecations, see How to deprecate classes, methods, arguments and hooks in the TYPO3 core.