TYPO3 Core

Hi,

I upgraded a system from 4.5 to 6.2 and now I try to update/create extensions.
The problem is, as soon as there is a php error, like an unknown function inside the an ActionController, it results in a white page and there are no errors to find in the logs.
Php errors are logged outside of typo3, e.g. I create a php file and call an undefined function, I will get: PHP Fatal error: Call to undefined function foo() in /var/www/foo.php on line

I tried multiple different settings for the [SYS]* configs.
Currently it is:

        'SYS' => array(
                'clearCacheSystem' => '1',
                'compat_version' => '6.2',
                'debugExceptionHandler' => 'TYPO3\CMS\Core\Error\DebugExceptionHandler',
                'devIPmask' => '*',
                'displayErrors' => '1',
                'doNotCheckReferer' => '1',
                'enableDeprecationLog' => 'devlog',
                'enable_DLOG' => '1',
                'enable_errorDLOG' => '1',
                'enable_exceptionDLOG' => '1',
                'encryptionKey' => 'a4dc57dd2b865c7be0a01e85936fc7c4',
                'errorHandler' => 'TYPO3\CMS\Core\Error\ErrorHandler',
                'errorHandlerErrors' => '30466',
                'exceptionalErrors' => '20480',
                'productionExceptionHandler' => 'TYPO3\CMS\Core\Error\ProductionExceptionHandler',
                'setMemoryLimit' => '128',
                'sitename' => 'Department Mathematik',
                'sqlDebug' => '1',
                'systemLog' => 'file,/tmp/foo.log',
                'systemLogLevel' => '0',
                't3lib_cs_convMethod' => 'iconv',
                't3lib_cs_utils' => '',
        )

The systemLog output in /tmp/foo.log looks like:

29-04-15 21:55 - cms: $TSFE->set_no_cache() was triggered. Reason: config.no_cache is set. Caching is disabled!
29-04-15 21:55 - cms: $TSFE->set_no_cache() was triggered. Reason: no_cache has been set before the page was generated - safety check. Caching is disabled!
29-04-15 21:55 - cms: Locking [simple::440d26b84dd230fc4accebdfb2c0476f]: Lock acquired
29-04-15 21:55 - cms: Locking [simple::440d26b84dd230fc4accebdfb2c0476f]: Acquired lock
29-04-15 21:55 - cms: $TSFE->set_no_cache() was triggered. Reason: config.no_cache is set. Caching is disabled!
29-04-15 21:56 - cms: $TSFE->set_no_cache() was triggered. Reason: config.no_cache is set. Caching is disabled!
29-04-15 21:56 - cms: Locking [simple::440d26b84dd230fc4accebdfb2c0476f]: Lock acquired
29-04-15 21:56 - cms: Locking [simple::440d26b84dd230fc4accebdfb2c0476f]: Acquired lock
29-04-15 21:56 - cms: $TSFE->set_no_cache() was triggered. Reason: config.no_cache is set. Caching is disabled!
29-04-15 21:56 - cms: $TSFE->set_no_cache() was triggered. Reason: config.no_cache is set. Caching is disabled!
29-04-15 21:56 - cms: Locking [simple::440d26b84dd230fc4accebdfb2c0476f]: Lock acquired
29-04-15 21:56 - cms: Locking [simple::440d26b84dd230fc4accebdfb2c0476f]: Acquired lock
29-04-15 21:56 - cms: $TSFE->set_no_cache() was triggered. Reason: config.no_cache is set. Caching is disabled!

Please, I need some help. Without any php errors, debugging of extension errors is horrible.

Thank you,
Bjoern