Always use trainers in offline mode. Using trainers in public multiplayer or online co-op can lead to bans or, at the very least, disrupt the experience for other players.
This usually indicates a version mismatch. If your game updated recently on Steam, the trainer's memory offsets might be outdated. Check the WeMod app or MrAntiFun forums to see if a newer version of the trainer has been released. The Game Crashes When Activating a Cheat resident evil 5 trainer mrantifun
Back up your save file before using any trainer. Your save is typically located in Documents\CAPCOM\RESIDENT EVIL 5\ . If the trainer corrupts it (rare, but possible), you’ll be thankful for the backup. Always use trainers in offline mode