Problem with group owner after update

Hello,
I have just update all my drupal sites with drush.
For the first time I use “root” access to do a “drush up drupal”
But I have 500 error because the file updated has wrong ownership.
All the files are in root owner…
How can I change this now ?
Regards,

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/21/feed