What causes GameMaker collisions not working?

The sprite has no collision mask, you are checking the wrong object or function, or the instances are not overlapping at the moment you check — masks and the right collision function matter.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix Collisions Not Working in GameMaker

Quick answer: Give the sprite a collision mask, use the correct check (place_meeting, instance_place, or collision_line) against the right object or parent, and verify the mask actually covers the sprite.

Collisions that never register in GameMaker usually come down to a missing mask or checking the wrong thing. Here is how to set up detection that works.

How to fix it

1. Set a collision mask

Each sprite needs a collision mask. If it is set to a tiny region or none, nothing collides. Open the sprite and confirm the mask covers the visible shape.

2. Use the right check function

place_meeting tests a position against an object, instance_place returns the instance hit, collision_line checks a ray. Use the one that matches what you need, and pass the correct object or parent.

3. Confirm overlap at check time

Collision functions test the current positions. If you move and check in the wrong order, or check before moving, instances may not overlap yet. Order movement and checks deliberately.

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.

Most of the time the fix is small. Seeing the failure clearly is the part that actually costs you.