Why won't my game's save file load?

Usually one of three reasons: the save is corrupt (often from a crash or interrupted write during a previous save), it's in an old or incompatible format (common after an update changed the save format), or the file can't be read (wrong path, permissions, or missing). The load error and where it fails, deserialization, version parsing, or file access, tell you which.

Why won't old saves load after I updated my game?

Because the update changed the save format, and the new version's loading code can't parse data written by the old version. The fix is to version your save format and add migration that upgrades old saves to the new format so they still load. A wave of load failures right after an update is the signature of this format-mismatch problem.

How do I stop a bad save from crashing my game?

Load defensively: validate the save data, and if it's corrupt or unreadable, catch the error and fail gracefully, fall back to a default or a backup save rather than crashing. Keep a backup of the previous good save as a safety net. And fix save-writing to be atomic so saves don't get corrupted in the first place. This turns a save that won't load from a crash into a recoverable situation with minimal progress lost.

How to Fix a Save File That Won't Load

Quick answer: A save file that won't load fails for one of a few reasons: the data is corrupt, it's in an old or incompatible format (often after an update), or the file can't be read (wrong path, permissions, missing). Capture the load error to see which, add format versioning and migration so old saves still load, validate the data, and make loading defensive so a save that genuinely can't be loaded fails gracefully rather than crashing or silently losing the player's progress.

A save that won't load is a serious problem, the player's progress is there but inaccessible, which feels like (or becomes) lost progress. The causes are a small, diagnosable set, and the fixes both recover loadable saves and ensure that even genuinely-broken ones fail in a controlled, non-crashing way rather than taking down the game.

Why a Save Won't Load

Save-load failures come from a few causes. Corruption: the save data is damaged (often from a crash or interrupted write during a previous save), so deserializing it fails. Format/version mismatch: the save was written by a different (usually older) version of the game with a different data format, and the current version's loading code can't parse it, a very common cause after updates. And read/access failures: the file is missing, in the wrong location, or can't be read due to permissions or storage issues.

Distinguishing them matters because the fixes differ. A corruption failure points at your save-writing robustness; a format mismatch points at versioning/migration; a read failure points at file handling. The load error and where it fails tell you which.

How to Diagnose It

Capture the load error and trace. A failure in deserialization points at corrupt or incompatible data; a file-not-found or permission error points at access; a version-related parse failure points at a format mismatch. If the problem started after an update, it's almost certainly a format/version mismatch (the update changed the save format). If it correlates with certain devices, it may be storage/permissions specific to those.

Bugnet captures the error context and device info with crashes and reported issues and tags the build version, so save-load failures arrive with the evidence to classify them, and a version-correlated wave of load failures right after an update immediately signals a format-migration problem. Because a save that won't load is high-impact (lost progress), treat these as priority even at modest volume.

How to Fix It

For format/version mismatches, handle old formats: version your save data and add migration so saves written by previous versions are upgraded and loaded rather than rejected (and going forward, always version the format so future changes don't break old saves). For corruption, the immediate fix is defensive loading, validate the save and, if it's unreadable, fail gracefully (fall back to a default or a backup) rather than crashing; longer-term, fix the save-writing to be atomic so saves don't get corrupted in the first place. For access failures, ensure the save path and permissions are correct on each platform and handle a missing/unreadable file gracefully.

Keeping a backup of the previous good save is a valuable safety net, if the current save won't load, fall back to the backup so the player loses minimal progress rather than everything. After fixing, verify saves load correctly (including old-format saves via migration), and confirm load-failure reports drop. The dual goal: recover every loadable save, and make unloadable ones fail safely instead of crashing or silently wiping progress.

A save that won't load is corrupt, an old format, or unreadable. Add format migration, validate and load defensively, and keep a backup so a bad save fails safely, not catastrophically.