TYPO3 Core

• PHP is ran as mod_php on Apache
• I've checked with phpinfo() from the install tool, that the proper php.ini file is loaded and processed (changing the error_reporting value in there also showed an effect when echo'ing error_reporting() - but didn't solve the problem)

Without analysing your report in depth, one comment:

mod_php's php_admin_value can only be set on a "virtual host" (or global) webserver context, and is a setting which cannot be overridden by either .htaccess (where you only can set php_value) or PHP error_reporting() method. This it is a setting an admin can enforce upon a user of a virtual host, which he cannot override (which makes sense for memory_limit, max_execution etc..).

So in this case setting this won't let TYPO3 manipulate error_reporting, which it does in it's start-up scripts, for example tslib/index_ts.php.

Just a note: all pending PHP 5.4 patches were now submitted by Helmut, therefore the Core should now always set the correct error_reporting.

Maybe you can retry your tests now.

I also had the same problem and tried so many things for a few hours. I cloned a T3 system to a new Debian 7 server with PHP 5.4. I have set via .htaccess:

php_flag display_startup_errors off
php_flag display_errors off
php_flag html_errors off
php_value docref_root 0
php_value docref_ext 0

php_value error_reporting 0
php_value display_errors 0
php_value display_errors Off
php_value error_reporting 0

php_value display_errors 0
php_value error_reporting 30719

And via localconf.php:

$TYPO3_CONF_VARS['SYS']['exceptionalErrors'] = '30711';
$TYPO3_CONF_VARS['SYS']['errorHandlerErrors'] = '30711';

But it did not help. Opening phpinfo via install tool gives mie:
error_reporting local = 22519
error_reporting master = 30719

But when I set php_admin_value error_reporting 30711 in the apache configuration, the errors are gone and I have error_reporting local = 30711.
Like this:

    <Directory /var/www/vhosts/host/>
        Options Indexes FollowSymLinks MultiViews
        php_admin_value error_reporting 30711
        AllowOverride All
        Order allow,deny
        allow from all
    </Directory>

So I think TYPO3 overwrites that values. If I ran phpinfo separately (not via Install Tool), it displays the same local value as the master value.

TYPO3 version ist 4.7.12.

Stumbled upon the same bug today on a machine with Ubuntu 14.04, PHP 5.5.9-1ubuntu4.5, PHP OPcache Version: 7.0.3FE

Same story as Bernhard Eckl described → »PHP Info« in Install Tool is showing the value »22519« for local error_reporting, regardless of any settings in Install Tool, or htaccess.

Therefore several »Strict Standards«-errors are shown in the frontend and backend (since they are part of E_ALL in PHP > 5.3).

Forcing the error_reporting parameter to a value using »php_admin_value« in the virtual host configuration buried the problem, since TYPO3 is not able to override the value afterwards. But of course, this isn't a good solution, since setting the option in the Install Tool if the prefereed method.

Btw: I searched for possible spots in the code for this behaviour, just as Tizian Schmidlin did in #51493, but can't find anything usefull.