After my update, players with old save files lose their progress

You rename one thing in the game and every existing save from before suddenly looks broken or empty. Players blame you, not the update. Here is a way to let old saves be upgraded step by step, and what to do with a save that comes from a newer version of the game.

Why this works

Players cannot be asked to start over, and you cannot foresee every old shape of a save. But you always know the one change between two neighbouring versions. Small steps in order turn any old file into the current one, and each step stays easy to check.

When not to use it

Skip the chain for a game still in private testing where saves are throwaway, or when the save is tiny and easy to rebuild. Then wiping old saves with a clear message costs less than keeping years of upgrade steps alive.

In the full entry

• What to build, step by step
• Starting values and the reason for each
• 3 common mistakes and the fix
• 44 lines of example code with 4 checks that pass
• How your AI shows you that it works

Say this to your AI

Use the Spielerando entry "After my update, players with old save files lose their progress" (read_entry old-saves-break-after-an-update-migration-chain) in my game. Build it step by step, and show me how you checked that it works.

Or skip this and connect the MCP: your AI then finds all of this by itself.Connect the MCP