Under Debian 8 (Jessie), the default configuration doesn't work, because the permission on the Apache log file doesn't allow to be accessed by the www-data user.
To fix this
create 640 root admby
create 644 root adm,
apache2log directory (
chmod +rX /var/log/apache2).
You may also have to enable the apache cgi mod (
a2enmod cgi). Don't forget to restart Apache.
By default, the
LogFormat entry value in the configuration file is set to
4, which doesn't match the default log format of apache. It should be set to