Why did my game's saves stop loading after an update?

Because the update changed the save data format, often as an unintended side effect of altering a data structure, and the new version's loading code can't parse data written in the old format. Saves that loaded fine before the update fail right after it, hitting players who had existing progress. It's a backward-compatibility regression in your save format.

Can I recover saves already broken by an update?

Yes, add migration code that detects the old format and upgrades it to the new one, which recovers the broken saves for players who already updated, they'll load on the next patch. Keep a backup of saves as a fallback in case migration fails. The migration both fixes the affected players and prevents the issue going forward by making old saves loadable rather than rejected.

Why Won't My Save Files Load After an Update?

Q: How do I make save files survive game updates?

Use save versioning and migration: tag each save with a format version, and on load, detect old-format saves and run migration code that upgrades them to the current format (defaulting new fields, transforming changed structures) so they still load. Always version your format and add migration for each change, so updates stay backward-compatible, and test loading old saves whenever you change save-related data.

Quick answer: Your save files won't load after an update because the update changed the save data format, often as an unintended side effect of altering a data structure, and the new version's loading code can't parse saves written in the old format. Saves that loaded fine before the update fail right after it. The fix is save versioning and migration: detect old-format saves and upgrade them rather than rejecting them.

Saves breaking after an update is a common, painful regression, players who updated suddenly can't load their progress, because the update inadvertently broke save compatibility. It happens whenever a code change alters how save data is structured without accounting for existing saves.

Why Updates Break Saves

Saves are serialized game state, and the format is tied to your data structures and save code. When an update changes those, adds or removes fields, renames things, restructures data, the format changes too. Now the new version's loading code expects the new format, but existing saves are in the old format, so loading them fails (a deserialization error). The update broke backward compatibility with old saves, often unintentionally, you changed a data structure for a feature, not realizing it altered the save format.

The signature is unmistakable: saves that loaded fine before the update fail right after it, hitting players who had existing progress. A wave of save-load failures immediately after an update is the giveaway.

How to Diagnose and Fix It

Version-tagged data confirms it: load failures spike on the new version among players who had old saves. Bugnet tags reports and crashes by build version, so a wave of save-load failures right after an update, concentrated among updating players, immediately signals a save-format regression, the version correlation is the giveaway, letting you catch it fast.

Fix with save versioning and migration: tag each save with a format version, and on load, detect old-format saves and run migration code that upgrades them to the current format (defaulting new fields, transforming changed structures) so they still load, which also recovers the already-broken players. Always version your format going forward and test loading old saves whenever you change save-related data. See our guide on fixing save files that break after an update.

Saves breaking after an update means the format changed and old saves no longer parse. Version your save format and migrate old saves forward, so updates upgrade saves instead of breaking them.