How to Reduce False Positives from Grim Anticheat

Why False Positives Happen

Grim predicts what a legitimate player's movement and actions should look like. When server lag, client lag, or unusual but legal mechanics cause the player's actual behavior to differ from the prediction, the anticheat flags them. Reducing false positives is about helping Grim distinguish lag from cheating.

Check Your Server Performance

Low TPS and frequent lag spikes are the most common cause of false positives. If your server is struggling, players will appear to teleport or move erratically from the anticheat's perspective. Fix performance issues first: reduce entity counts, optimize chunk loading, and ensure your host has adequate resources.

Review Problematic Checks

Look at which checks are firing most often against players you trust. If a specific check is responsible for most false positives, raise its threshold or disable it temporarily while you investigate. Document every change so you can revert if needed.

Account for Legitimate Mechanics

Features like elytra flight, ice boats, pistons, and slime blocks produce movement that can look suspicious. Make sure your Grim configuration is aware of these mechanics, or raise thresholds for the affected checks. Test each mechanic on your server after configuration changes to confirm it no longer triggers alerts.

Communicate With Players

If players report being kicked unfairly, ask for the timestamp and what they were doing. Correlate with your logs and the anticheat report to identify the pattern.