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 PlayerPrefs Loss When the App Crashes Before Flushing

Q: What causes Unity PlayerPrefs loss when the app crashes before flushing?

PlayerPrefs keeps values in memory and only writes them to disk on a normal quit or an explicit Save call, so a crash before that point discards everything set this session.

Q: How do you fix Unity PlayerPrefs loss when the app crashes before flushing?

Call PlayerPrefs.Save() immediately after writing important values and on pause, so the data is flushed to disk and survives a crash.

Quick answer: Call PlayerPrefs.Save() immediately after writing important values and on pause, so the data is flushed to disk and survives a crash.

PlayerPrefs buffers writes in memory and flushes on clean exit. A crash loses everything not yet written. Call Save() after important changes to harden against it.

How to fix it

1. Flush after important writes

After setting values that matter (purchases, unlocks), call PlayerPrefs.Save() right away instead of waiting for the implicit flush on quit.

2. Save on pause for mobile

In OnApplicationPause(true), call PlayerPrefs.Save() since mobile crashes and kills often skip OnApplicationQuit.

3. Avoid excessive flushing

Save() does synchronous disk I/O, so do not call it every frame. Flush on meaningful state changes and lifecycle events, not in a tight loop.

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.

Most of the time the fix is small. Seeing the failure clearly is the part that actually costs you.