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 a Level Transition Loading the Player at the Wrong Entrance in GameMaker

Q: What causes a level transition loading the player at the wrong entrance?

Room transitions always place the player at a single default spawn, ignoring which door they used, so entering a room from the right still spawns them at the left entrance.

Quick answer: Pass the destination door id through the transition, and on room start position the player at the matching entrance instead of a single hardcoded spawn point.

In connected levels the player should arrive at the door that matches the one they left. The fix is to carry the target entrance id across the transition and spawn there.

How to fix it

1. Carry the target door id

When a door triggers a transition, store the destination room and the id of the matching entrance in globals before room_goto, so the next room knows where to place the player.

2. Spawn at the matching entrance

On the new room's creation, find the entrance object whose id matches the stored target and move the player there, instead of using a fixed default spawn for every entry.

3. Pair doors consistently

Give each connected door pair matching ids so leaving through a door always arrives at its counterpart, keeping the world's connectivity coherent during backtracking.

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.

Reproduce it once with full context and the fix writes itself. The hunt is the expensive part.