What causes Unity DontDestroyOnLoad objects piling up on restart?

Restarting by reloading the boot scene re-runs the manager's Awake and calls DontDestroyOnLoad again, but the previous persistent instance survives, so copies accumulate every restart.

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 Unity DontDestroyOnLoad Objects Piling Up After Repeated Restarts

Quick answer: Enforce a singleton guard in Awake that destroys the new duplicate when an instance already exists, so restarting never adds a second persistent manager.

Marking a manager DontDestroyOnLoad means it survives scene loads, including the boot scene reload you use to restart. Without a duplicate guard, each restart leaves another copy alive.

How to fix it

1. Add a duplicate guard in Awake

If a static Instance is already set, call Destroy(gameObject) and return before any other setup, so only the original persists.

2. Restart without reloading the boot scene

Prefer resetting state and loading the first gameplay scene over reloading the scene that spawns persistent managers, removing the duplicate source entirely.

3. Reset state on the surviving instance

On restart, call a reset method on the existing manager rather than relying on a freshly spawned one, so persistent objects stay singular.

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 Unity 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.