Game refuses to load when using an old save file from 6.0.0 and just freezes up for me. Deleting the save fixes the problem though. Not entirely sure if I'm just being dumb or not.
I might have spotted where the issue is after a bunch of trial and errors in the registries. The char0, char1, char2, char3 values from the old versions became too big to handle for the game. Everything else works. If there's a way to "slim them up", the game should work smoothly. I tried starting a new game and only added the old char0 value keeping the default ones for the other three, it managed to load it after a bit, but back to level 1 with no exp. It might be something that has to deal with how exp is saved in the files or something, since once the character's exp was removed the game started loading again.
Unfortunately, it has nothing to do with the char0-3 values. They worked fine before, even as far back as version 4. (2 years ago)
(And besides, the exps aren't saved in the char0-3. They're saved somewhere else)
I made an additional information in the post above to temporarily fix the issue, where it will change a small part of the save data.
But hopefully, you won't need to do this anymore in version 6.1.3.
Edit:
As mentioned by another person, the char0-3 may have indirectly contributed to this error, but not because of how big their save data is. I'll investigate this either way.
It's fixed, thank you very much :) My characters are back, even if at level 1. Some have 7 hours of playtime (as old as 4.0 over there), was more bummed about missing them than their exp, which can be farmed again. I reported in a previous comment days ago the "invisible" color missing from the palette, but now it's also working again as intended. Excited to try out the combo of news saying what the levels actually drop and the reduced prices in the boost shop.
On a unrelated note, may I ask you if you're planning to also add new clothes in the future?