What causes a Construct 3 value shared across all instances instead of per-instance?

The value is stored in a global (or static) variable, which is shared by every object, so setting it for one instance overwrites it for all of them.

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 Construct 3 Value That Should Be Per-Instance But Is Shared

Quick answer: Replace the global with an instance variable on the object so each instance carries its own copy, and reference it as Object.varName per picked instance.

A global holds one value for everyone; per-object state needs an instance variable. Moving the value onto the object gives each instance its own. Here is how.

How to fix it

1. Add an instance variable

Select the object type and add an instance variable (for example health). Every instance then has its own copy that other instances cannot affect.

2. Set it on the picked instance

Inside an event that picks a specific instance, set Object.health. The assignment applies only to the instances currently in the picked list, not all of them.

3. Stop using a global for per-object state

Remove the global you were using for this and migrate reads to Object.varName. Globals are correct only for state truly shared by all instances or the whole game.

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 Construct 3 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.