Configuration of the logging system

The instantiation of loggers is configuration-free, as the log manager automatically applies its configuration.

The logger configuration is read from $GLOBALS['TYPO3_CONF_VARS']['LOG'], which contains an array reflecting the namespace and class hierarchy of your TYPO3 project.

For example, to apply a configuration for all loggers within the \TYPO3\CMS\Core\Cache namespace, the configuration is read from $GLOBALS['TYPO3_CONF_VARS']['LOG']['TYPO3']['CMS']['Core']['Cache']. So every logger requested for classes like \TYPO3\CMS\Core\Cache\CacheFactory, \TYPO3\CMS\Core\Cache\Backend\NullBackend, etc. will get this configuration applied.

Configuring the logging for extensions works the same.

Writer configuration

The log writer configuration is read from the sub-key writerConfiguration of the configuration array:

config/system/additional.php | typo3conf/system/additional.php
$GLOBALS['TYPO3_CONF_VARS']['LOG']['writerConfiguration'] = [
    // Configuration for ERROR level log entries
    \Psr\Log\LogLevel::ERROR => [
        // Add a FileWriter
        \TYPO3\CMS\Core\Log\Writer\FileWriter::class => [
            // Configuration for the writer
            'logFile' => \TYPO3\CMS\Core\Core\Environment::getVarPath() . '/log/typo3_7ac500bce5.log'

The above configuration applies to all log entries of level "ERROR" or above.


The default folder for log files is <var-path>/log. The <var-path> is <project-root>/var/ for Composer-based installations and typo3temp/var/ for legacy installations.

To apply a special configuration for the controllers of the examples extension, use the following configuration:

config/system/additional.php | typo3conf/system/additional.php
$GLOBALS['TYPO3_CONF_VARS']['LOG']['T3docs']['Examples']['Controller']['writerConfiguration'] = [
    // Configuration for WARNING severity, including all
    // levels with higher severity (ERROR, CRITICAL, EMERGENCY)
    \Psr\Log\LogLevel::WARNING => [
        // Add a SyslogWriter
        \TYPO3\CMS\Core\Log\Writer\SyslogWriter::class => [],

This overwrites the default configuration shown in the first example for classes located in the namespace \T3docs\Examples\Controller.

One more example:

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

// For class \T3docs\Examples\Controller\FalExampleController
    ['writerConfiguration'] = [
        // ...

// For channel "security"
$GLOBALS['TYPO3_CONF_VARS']['LOG']['security']['writerConfiguration'] = [
    // ...

For more information about channels, see Channels.

An arbitrary number of writers can be added for every severity level (INFO, WARNING, ERROR, ...). The configuration is applied to log entries of the particular severity level plus all levels with a higher severity. Thus, a log message created with $logger->warning() will be affected by the writer configuration for the log levels:

  • LogLevel::DEBUG

  • LogLevel::INFO

  • LogLevel::NOTICE

  • LogLevel::WARNING

For the above example code that means:

  • Calling $logger->warning($msg); will result in $msg being written to the computer's syslog on top of the default configuration.

  • Calling $logger->debug($msg); will result in $msg being written only to the default log file (var/log/typo3_<hash>.log).

For a list of writers shipped with the TYPO3 Core see the section about Log writers.

Processor configuration

Similar to the writer configuration, log record processors can be configured on a per-class and per-namespace basis with the sub-key processorConfiguration:

config/system/additional.php | typo3conf/system/additional.php
$GLOBALS['TYPO3_CONF_VARS']['LOG']['T3docs']['Examples']['Controller']['processorConfiguration'] = [
    // Configuration for ERROR level log entries
    \Psr\Log\LogLevel::ERROR => [
        // Add a MemoryUsageProcessor
        \TYPO3\CMS\Core\Log\Processor\MemoryUsageProcessor::class => [
            'formatSize' => TRUE

For a list of processors shipped with the TYPO3 Core, see the section about Log processors.