Unknown engine type outputformat Hello I've just updated Drupal (to version 7.53) and now in Drush when I try launch the commands:
"drush @theflyingeye.org up" (to update my website)
or
"drush @theflyingeye.org cc" (to clean chache)
or
"drush @theflyingeye.org dl view" (to download a basic module, view for example)
I can just get this answer:
"Unknown engine type outputformat"

If I digit:

"drush status" (after "su aegir")
I can get: 
"PHP configuration     :  /etc/php5/cli/php.ini                                 
 Drush version         :  5.10.0                                                
 Drush configuration   :  /var/aegir/.drush/drushrc.php                         
 Drush alias files     :  /var/aegir/.drush/server_master.alias.drushrc.php     
                          /var/aegir/.drush/theflyingeye.org.alias.drushrc.php  
                          /var/aegir/.drush/server_localhost.alias.drushrc.php  


Do you have any advise please to fix this problem?
Start with upgrading to Drush 8 ... see http://drush.org/en/master/install