What causes a save file ballooning from serialized runtime-only data?

The serializer walks fields that hold caches, pooled objects, or computed data, writing megabytes of derived state that should be recomputed at load instead.

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 Save File Ballooning From Serialized Runtime-Only Data

Quick answer: Mark caches and pooled/runtime fields as non-serialized, and persist only the minimal authoritative state needed to reconstruct everything else on load.

Saves bloat when the serializer follows fields holding caches, pools, or rendered data. Persist only source-of-truth state and recompute the rest on load to shrink files.

How to fix it

1. Audit what is being written

Inspect the save's size and dump its keys. Caches, lookup tables, and pooled object lists are common culprits that should never be persisted.

2. Mark transient fields non-serialized

Annotate derived or runtime-only fields so the serializer skips them (for example [NonSerialized] in C#, @JsonIgnore, or excluding them in your custom writer).

3. Recompute on load

Persist only authoritative state (inventory IDs, positions, flags) and rebuild caches, indices, and pooled objects after the load completes.

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 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.