Effectivement, sur le forum de rockstar:
http://www.rockstargames.com/newswire/article/6491/free_red_dead_redemption_outlaws_to_the_end_co-op_mission_pack_downloadable_content_now_available.article
(une personne de rockstar): forum rockstar
Hey guys,
Thanks for your patience. We've isolated the issue with the free DLC mission pack that was causing broader problems with Red Dead Redemption's multiplayer, and we've implemented a fix that is now live on both platforms. This update is now in place (you will not be prompted to download anything, but you may need to restart your game in order for it to take effect).
The update also closes an XP exploit whereby players could trigger empty Gang Hideouts and have them register as complete.
For anyone still experiencing issues, please contact our technical support team for assistance through any of the following means:
E-mail: RDRSupport@rockstargames.com
Web: www.rockstargames.com/support
Twitter: twitter.com/rockstarsupport