After upgrade to 4.7.13, I get 500 Internal Server Error when creating new mailing
After investigations : 


The issue is due to i18n : if multilingual is on, then the bug raises. When it's off, there are no bug.
CRM_Core_DAO_AllCoreTables::registerEntityType returns only table names without language code. In my case, the function returns civicrm_group instead of civicrm_group_fr_FR. Then, the function CRM_Core_DAO_AllCoreTables::getClassForTable($table) returns nothing, which ends with the following error : PHP Fatal error:  Class name must be a valid object or a string in /store/www/dev.lists.sciences-po.fr/html/sites/all/modules/civicrm/CRM/Utils/SQL.php on line 53


Guess some hook in the i18n module is missing or not working properly.