Hi,
thanks for the answer. I try to set
# Displaying PHP errors
php_flag display_errors on
php_value error_reporting 6143
into .htaccess file, but a badly server error appears. I had to change in the previous version the .htaccess so the site turn back normaly. I really think that my hosting provider can't give me the possibility to modify this data. After that I connect to my domain administration page and I find all the apache error log file

I think is what we need.
So I find:
[Mon Jan 12 08:07:01 2015] [alert] [client xxx.xxx.xxx.xxx] /home/xxxxx/domains/xxxxxxxx/public_html/.htaccess: Invalid command 'php_flag', perhaps misspelled or defined by a module not included in the server configuration
That, for me, means that the hosting provider block me for the having the error display. After that I'm try to download a single file, obiuvsly I received a blank page. Here is the error in the error log file.
[Mon Jan 12 08:11:21 2015] [warn] [client xxx.xxx.xxx.xxx] mod_fcgid: stderr: PHP Fatal error: Call to undefined method RuntimeException::get() in /home/xxxxxx/domains/xxxxxxxxx/public_html/templates/yoo_cloud/error.php on line 20
Is what you need? How can I solve the problem?
Thanks in advance
Gianluca