The save is the problem, not the files. Try a save that was done at the start of 0.30.0 if possible.
EDIT: In additionally, you can ignore that. Then go to the debug screen to check are the variables to your liking.
I started from a save back in 0.29.0 (with the patch 0.31.1 installed) and still get the same error during the transition from 0.30.0 to 0.31.1. I could definitely change the variable through the dev screen to True but it seems that this error would still persist in any release.