What causes a full container deleting overflow items?

The transfer removes items from the source first and then tries to add them to a full destination, dropping whatever does not fit.

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 Full Container Deleting Items Instead of Refusing the Transfer

Quick answer: Compute how much the destination can accept before moving anything, transfer only that amount, and leave the remainder in the source.

A player shift-clicks a stack into a nearly full chest and part of it just vanishes. The transfer pulls from the source before confirming the destination has room.

How to fix it

1. Check capacity before moving

Calculate the destination's free space for the item, including partial stacks, before removing anything from the source. Removing first and adding second is what destroys overflow.

2. Move only what fits

Transfer the acceptable amount and leave the rest in the source slot so nothing is lost. Then show feedback that the container is full.

3. Make the transfer atomic

Treat the move as a single operation that either fully or partially succeeds without ever entering a state where items exist in neither container.

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.