What causes the data-structure-does-not-exist error in GameMaker?

Code used a ds_list/ds_map/ds_grid ID that is not alive — the structure was destroyed and then accessed, never created on this code path, or an ID variable was overwritten (or reused after destroy).

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 “Data structure with index does not exist” in GameMaker

Quick answer: Create structures before use on every path, null your ID variables after destroy, and audit ownership so exactly one place creates and one destroys each structure.

DS structures are handles, not values: destroy one and every copy of its ID dangles. This error is a dangling handle being used. Here is the ownership discipline that ends it.

How to fix it

1. Pair create and destroy explicitly

Each ds_map_create() needs exactly one ds_map_destroy() — typically Create and Clean Up events of the owning object; destruction anywhere else is where dangles start.

2. Mark destroyed IDs

After ds_list_destroy(list), set list = -1; and guard uses with if (list != -1) — IDs get recycled, so a stale ID may silently read someone else's structure before it errors.

3. Check the creation path

Structures created in an event that did not run (room-specific Create, conditional init) leave other events accessing nothing — initialize in a guaranteed-early event.

4. Consider structs instead

Modern GML structs and arrays are garbage-collected and cannot dangle — new code rarely needs ds_* structures at all.

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.

The errors you never hear about are the ones quietly costing you players. Visibility turns them into a worklist.