Yeah, that error is not exactly something Arc can fix.
As the thing says:
“Couldn’t find a place to stop rolling back. Perhaps the script changed in an incompatible way?”
It’s because of the nature of the game, it being a work in progress.
Sometimes saves may break if Arc changes the script (rewrites, typos, etc)
That why ideally you should try saving in “safe spots” and avoid saving in the middle of dialogue.
An example of a safe spot would be the MC’s bedroom.
Which is why the autosave only saves every time you go to sleep.
(Check the A page in the save menu, you might have one there.)