Monster Hunter World: Iceborne players are reporting they’re losing save data after the new expansion. Capcom confirmed it’s looking into the issue.

Capcom released its Iceborne expansion for Monster Hunter: World on Steam on Thursday, and some players are reporting problems with their save data. Specifically, players on Reddit and theSteamforums appear to have their old saves overwritten when previous saves are unable to load.
Upon loading the game, players are getting an error message that says theres no compatible save if you continue and start a new game, a new save filed is created and appears to overwrite the old save, according to a report from VG24/7.
Capcom told Polygon its aware and are looking into the issue. No further information is immediately available.
Players have a few theories, from issues with mods to an uninstalled previous update that adjusted save data formatting. At this time, players are recommending to each other to back up their cloud save data on Steam before attempting to play Iceborne, else risk losing their data.
Monster Hunter World: Iceborne was first released on PlayStation 4 and Xbox One on Sept. 6, 2019. Once youve begun playing on PC, itll absolutely be worth your time to complete the Beef is Never a Mi-Steak quest, which will award you the parts to create a giant chicken drumstick weapon.
Update, Jan. 15: Capcom will release a patch in the coming days to address the save data issue.
In a post on Steam, Capcom said the issue was with games that havent been updated after Oct. 30, 2018. Save data was not being converted to the new file format. In the interim, players are advised to shut down Monster Hunter World: Iceborne when the Failed to read saved data message appears.