What causes a Unity app state machine skipping states during Enter?

A state calls the transition method from inside its Enter, re-entering the state machine before the current Enter finished, which corrupts the current-state field and skips or duplicates states.

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 Unity App State Machine That Skips States Because Transitions Fire During Enter

Quick answer: Queue requested transitions and process them once per frame in Update, so a state never changes state synchronously from within its own Enter or Exit.

A global app state machine that drives boot, menu, playing, and paused must never transition re-entrantly. Letting Enter trigger another transition mid-call leaves the machine in an inconsistent state.

How to fix it

1. Queue instead of switching immediately

Have ChangeState store the requested next state in a field rather than swapping right away. Apply it at a single, safe point in the loop.

2. Process one transition per tick

In the state machine's Update, if a pending state is queued, run the current state's Exit, swap, and run the new Enter, then clear the queue.

3. Forbid synchronous re-entry

Assert if a transition is requested while one is already being applied, so re-entrant transitions surface in development instead of silently corrupting state.

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 bug you can't reproduce isn't gone — it's just invisible until you capture it from the player's device.