Start a new save in the released game
If the crash follows loading or continuing a demo-era save, the official guidance is clear: start a new save in the released game. The demo save is not compatible with the release build.
Do not treat old demo advice as current
The demo, playtest and released game are different build contexts. Avoid following an old workaround that promises to convert, repair or reuse a demo save unless a current official announcement confirms it.
When the issue is not a demo save
This page only covers the confirmed demo-save compatibility problem. For a crash on a newly created release save, consult the latest official Steam announcements or support channels and include the current game version and a clear description of when the crash occurs.