When launching Halo: Reach via Steam or Microsoft Store, you will not be able to play the title’s matchmaking options if you select the launch option labeled “EAC Bypass” as this disables Easy Anti-Cheat. This specific feature enables users who would like to modify content and play online through custom games and campaign content without issues.
If you modify content while in this mode, you will not be able to simply play when turning the option off. You will need to backup the un-modified content to restore the game files to what were originally downloaded before being able to matchmake again. If you’re not familiar with modding and altering core files, please use caution as you could inadvertently end up in a bad state. We highly recommend making a backup core game files before attempting any modding.
To exit the EAC Bypass mode, simply exit and relaunch the title. On relaunch, make sure you are selecting “Play Halo: The Master Chief Collection.”
If you do not restart the client and attempt to play a matchmade offering, you will receive the following error:
You cannot matchmake because Easy Anti-Cheat isn’t enabled.”