"Foreman Export could not be completed - possible mod conflict detected. Please run factorio and ensure it can successfully load to menu before retrying."

I can load to menu and start a new save in factorio without any issues, and game and mod paths are definitely set correctly. How do I find out where the issue comes from?
The factorio log doesn't show any errors (some normal script output up to 8.6 seconds, and then "Goodbye" at 9.0)...