An update addresses the issue of achievement in Left 4 Dead 2

Achievements unlocked again Valve has released a patch for 2 Left 4 Dead Xbox 360 version that aims to solve several problems related to the famous horror shooter multiplayer. In addition to bug fixes, balance changes and added some options to the various game modes, the upgrade should replace the damage caused by the release of the objectives unlockable DLC The Sacrifice, after which several people found out about the removal or suspension won several achievement.

For full details on the contents of the patch please see the link below. Source: Left 4 Dead Blog

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