Unable to install v.4.6.x - Drupal7
I finally succeeded to find the solution!

It was the VirtualHost's include_path the problem! In fact it seems that CiviCRM's install script needs to add paths in it, and if it is already set, it cannot be modified with the PHP's native function set_include_path(void).

So, I only had to comment the VirtualHost's include_path, and it worked!

My VirtualHost looks like that now:


 &lt;VirtualHost 192.168.1.203:80&gt;
     ServerName xxxx
     SetEnv CODE_SITE xxxx
     DocumentRoot /var/www/xxxx  
     php_admin_flag  engine on
     #php_admin_value include_path "/var/www/xxxx/" =&gt; this line must be deleted
&lt;/VirtualHost&gt;