@egon0 Oh that definitely looks like display_errors=on to me. Maybe you could edit your other php.ini files just for fun? (or maybe some site-specific configuration, like directives in the webserver or .htaccess or whatever?)

And make sure you restart both your webserver and php5-fpm daemon to be sure settings are in effect.

Maybe you could verify this by triggering an error in a custom php file that _only_ contains a faulty PHP statement? :)
<?php
var_dump(ini_get('display_errors'));
$test = array();
echo $test['doesnotexist'];