-. Error 500
.htaccess File contains Options +FollowSymLinks but the serveur not allow, so replace Options +FollowSymLinks by Options +SymLinksIfOwnerMatch
-. Xdebug settings
Xdebug settings xdebug.max_nesting_level is set to 100.
Set xdebug.max_nesting_level=256 in your PHP configuration as some pages in your Drupal site will not work when this setting is too low.
Goto : Webmin->Others->PHP Configuration
Enter /etc/php5/apache2/conf.d/20-xdebug.ini and click on 'Manage'
Click on : 'Edit Configuration Manually'
Add : xdebug.max_nesting_level=256
Save
Restart apache2
-. PHP Version
-. Database
Probleme / File
Clean URL : httpd.conf
OPcache : php.ini
​Xdebug : php.ini
...