What causes Godot ResourceSaver dropping fields from a custom Resource?

ResourceSaver only writes properties that are exported or otherwise registered with the property list, so plain script variables without @export are not persisted.

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 Godot ResourceSaver Dropping Plain Fields From a Custom Resource

Q: How do you fix Godot ResourceSaver dropping fields from a custom Resource?

Mark every field you want saved with @export (or implement _get_property_list) so the property is part of the resource's serialized state.

Quick answer: Mark every field you want saved with @export (or implement _get_property_list) so the property is part of the resource's serialized state.

ResourceSaver serializes a Resource's exported properties. A field declared as a plain var is invisible to it and silently dropped from the .tres. Adding @export saves it.

How to fix it

1. Export the fields

Change var coins = 0 to @export var coins := 0 on the custom Resource. Only exported (or explicitly listed) properties are written by ResourceSaver.

2. Use the right flags on save

Call ResourceSaver.save(resource, "user://save.tres"). Avoid bundling unrelated sub-resources unless you intend to, since flags like FLAG_BUNDLE_RESOURCES change what gets embedded.

3. Verify by reading back

Load with ResourceLoader.load("user://save.tres") immediately after saving and assert your fields round-trip. This catches missing @export before players hit it.

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 Godot 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.