How to Fix buffer_load Returning -1 and Broken Save Files in GameMaker

A -1 from buffer_load means no data — and code that indexes into a -1 buffer crashes next line. First runs and corrupted saves must both be survivable. Here is the robust loader.

How to fix it

1. Handle the no-file case first

if (!file_exists(fname)) { setup_defaults(); return; } — a fresh install has no save, and that path must be a designed experience, not an error.

2. Check the load result

var buf = buffer_load(fname); if (buf == -1) { /* corrupt or locked */ } — fall back to a backup save or defaults, and report the event to your error tracking.

3. Write atomically with a backup

Save to save.tmp, then delete old backup, rename current to backup, rename tmp to current — interrupted writes then never destroy the only copy.

4. Validate before use

Start files with a magic value and version; a size or header mismatch means corruption — refuse to parse garbage instead of crashing deeper in the load code.

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 GameMaker 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.