Why do saves corrupt after a crash?

Because if the crash happens while the game is writing the save, the write is interrupted partway, leaving a half-written, invalid file, that's the corruption, which then fails to load (sometimes causing a crash loop). Writing saves atomically (to a temp file, then renaming only after the write fully completes) ensures a crash mid-write leaves the previous good save intact instead of corrupting it.

Why Do My Save Files Get Corrupted?

Q: What causes save file corruption in games?

Overwhelmingly, an interrupted write: when the game is saving and the write is interrupted partway, by a crash during saving, the app being killed, power loss, or removable storage being pulled, the file is left half-written and invalid. That partial file is the corruption. A telltale sign is corruption appearing after crashes or force-quits, which interrupted the save in progress.

Q: How do I prevent save corruption?

Write saves atomically: write the new save to a temporary file, fully flush it to disk, and only then rename it into place over the real save. That way an interrupted write leaves the temporary file incomplete but the real save untouched, so an interruption can never corrupt the actual save. Add a backup of the previous save and validation on load as extra safety nets.

Quick answer: Your save files get corrupted almost always because a save write was interrupted partway, by a crash during saving, the app being killed, power loss, the player closing the game mid-save, or removable storage being pulled, leaving a half-written, invalid file. That partial file is the corruption, and it then fails to load. The fix is atomic writes so an interruption can't corrupt the real save.

Save corruption is one of the worst things for a player, their progress destroyed, and it generates fury and refunds. The good news is that corruption has a well-understood primary cause (an interrupted write) and a well-established fix (atomic writes). Most corruption isn't random; it's a half-completed write.

Why Saves Get Corrupted

The dominant cause is an interrupted write. When the game saves, it writes data to the file; if that write is interrupted partway, by a crash during saving, the app being killed, power loss, the player closing mid-save, or removable storage being pulled, the file is left half-written: partial, inconsistent, invalid. That partially-written file is the corruption, and it then fails to load (or loads as garbage).

A telltale sign is corruption that appears after crashes or force-quits, the interruption corrupted the save in progress. Other causes (bugs that write invalid data, storage-level corruption) exist but are far less common than the interrupted-write scenario.

How to Diagnose and Fix It

Corrupted saves show up as load failures (deserialization errors) or garbage loaded state, often correlated with prior crashes or force-quits. Bugnet captures crashes and reports with context, so a pattern of load failures or crash loops correlated with prior crashes (and concentrated where writes get interrupted, like devices with removable/managed storage) points at save corruption. Prioritize it, each corrupted save is a player who lost progress.

Fix it with atomic writes: write the new save to a temporary file, ensure it's fully flushed, and only then rename it into the real save location, so an interrupted write leaves the temporary file incomplete but the real save untouched. Add a backup of the previous save and validation on load. See our guide on fixing corrupted save files for the details. Atomic writes plus backups make corruption a largely solved problem.

Save corruption is almost always an interrupted write leaving a half-written file, often from a crash mid-save. Write atomically, temp file then rename, so an interruption never touches the real save.