Today's update to Forza Horizon 3 stands a high chance of corrupting your saved data, according to developer Playground Games.
Members of the dev team have been tracking the issue all day on the game's forums.
"PC players who completed the download of .37.2 and then started a new game save will have a corrupted saved game," according to a post published by a member of the Forza community team. "Avoid creating a new saved game on .37.2, and only play on .35.2 to avoid this issue. As long as you have an existing save and have not created a new one on .37.2, your saved game will work correctly once the update is available."
You can check your version number on the game's start-up screen.
As of this writing, the faulty version of Forza Horizon 3 has been removed. If your version ends in .37.2, uninstall the game and download it again. If you've started a download that hasn't finished, cancel it and wait for news of a fix.
It's unknown whether or not corrupted saves on PC will affect the Xbox One version of the game.