How to Fix a GameMaker AI Stuck Attacking a Dead Target

A GameMaker enemy that keeps attacking after its victim is already destroyed is holding a stale instance id. Adding an instance_exists check that clears dead targets fixes the loop. Here is how.

How to fix it

1. Validate the target each step

At the top of the attack state check if (!instance_exists(target)) { target = noone; } (and verify range); a destroyed instance id otherwise lingers and the AI swings at empty space.

2. Clear on the target's Destroy event

Have targets notify attackers, or simply rely on the per-step instance_exists guard, so the enemy stops the same step the target dies.

3. Reselect after clearing

Once target == noone, re-run target selection (e.g. instance_nearest over valid foes) so the AI engages the next enemy or returns to patrol.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every GameMaker error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.